numhask-0.12.0.2: A numeric class hierarchy.
Safe HaskellSafe-Inferred
LanguageGHC2021

NumHask.Prelude

Description

A prelude composed by overlaying numhask on Prelude, together with a few minor tweaks needed for RebindableSyntax.

Synopsis

numhask exports

rebindables

Using different types for numbers requires RebindableSyntax. This then removes base-level stuff that has to be put back in.

ifThenElse :: Bool -> a -> a -> a Source #

RebindableSyntax splats this, and I'm not sure where it exists in GHC land

fromList :: IsList l => [Item l] -> l #

The fromList function constructs the structure l from the given list of Item l

fromListN :: IsList l => Int -> [Item l] -> l #

The fromListN function takes the input list's length and potentially uses it to construct the structure l more efficiently compared to fromList. If the given number does not equal to the input list's length the behaviour of fromListN is not specified.

fromListN (length xs) xs == fromList xs

data Natural where #

Natural number

Invariant: numbers <= 0xffffffffffffffff use the NS constructor

Bundled Patterns

pattern NatJ# :: BigNat -> Natural 
pattern NatS# :: Word# -> Natural 

Instances

Instances details
Data Natural

Since: base-4.8.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Natural -> c Natural #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Natural #

toConstr :: Natural -> Constr #

dataTypeOf :: Natural -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Natural) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Natural) #

gmapT :: (forall b. Data b => b -> b) -> Natural -> Natural #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Natural -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Natural -> r #

gmapQ :: (forall d. Data d => d -> u) -> Natural -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Natural -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Natural -> m Natural #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Natural -> m Natural #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Natural -> m Natural #

Enum Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Enum

Num Natural

Note that Natural's Num instance isn't a ring: no element but 0 has an additive inverse. It is a semiring though.

Since: base-4.8.0.0

Instance details

Defined in GHC.Num

Read Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Read

Integral Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Real

Real Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Real

Show Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Show

Eq Natural 
Instance details

Defined in GHC.Num.Natural

Methods

(==) :: Natural -> Natural -> Bool #

(/=) :: Natural -> Natural -> Bool #

Ord Natural 
Instance details

Defined in GHC.Num.Natural

Additive Natural Source # 
Instance details

Defined in NumHask.Algebra.Additive

Subtractive Natural Source # 
Instance details

Defined in NumHask.Algebra.Additive

BoundedJoinSemiLattice Natural Source # 
Instance details

Defined in NumHask.Algebra.Lattice

JoinSemiLattice Natural Source # 
Instance details

Defined in NumHask.Algebra.Lattice

MeetSemiLattice Natural Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Basis Natural Source # 
Instance details

Defined in NumHask.Algebra.Metric

Associated Types

type Mag Natural Source #

type Base Natural Source #

Multiplicative Natural Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

InvolutiveRing Natural Source # 
Instance details

Defined in NumHask.Algebra.Ring

Methods

adj :: Natural -> Natural Source #

FromInteger Natural Source # 
Instance details

Defined in NumHask.Data.Integral

Integral Natural Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Natural Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Natural Natural Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Natural Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Natural Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Natural Natural Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Natural Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToRatio Natural Integer Source # 
Instance details

Defined in NumHask.Data.Rational

type Base Natural Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Mag Natural Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Compare (a :: Natural) (b :: Natural) 
Instance details

Defined in Data.Type.Ord

type Compare (a :: Natural) (b :: Natural) = CmpNat a b

Modules you can't live without

module Data.Bool

module Data.Kind

newtype Any #

Boolean monoid under disjunction (||).

>>> getAny (Any True <> mempty <> Any False)
True
>>> getAny (mconcat (map (\x -> Any (even x)) [2,4,6,7,8]))
True

Constructors

Any 

Fields

Instances

Instances details
Data Any

Since: base-4.8.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Any -> c Any #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Any #

toConstr :: Any -> Constr #

dataTypeOf :: Any -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Any) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Any) #

gmapT :: (forall b. Data b => b -> b) -> Any -> Any #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r #

gmapQ :: (forall d. Data d => d -> u) -> Any -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Any -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Any -> m Any #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any #

Monoid Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Any #

mappend :: Any -> Any -> Any #

mconcat :: [Any] -> Any #

Semigroup Any

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Any -> Any -> Any #

sconcat :: NonEmpty Any -> Any #

stimes :: Integral b => b -> Any -> Any #

Bounded Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

minBound :: Any #

maxBound :: Any #

Generic Any 
Instance details

Defined in Data.Semigroup.Internal

Associated Types

type Rep Any :: Type -> Type #

Methods

from :: Any -> Rep Any x #

to :: Rep Any x -> Any #

Read Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Show Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> Any -> ShowS #

show :: Any -> String #

showList :: [Any] -> ShowS #

Eq Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: Any -> Any -> Bool #

(/=) :: Any -> Any -> Bool #

Ord Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: Any -> Any -> Ordering #

(<) :: Any -> Any -> Bool #

(<=) :: Any -> Any -> Bool #

(>) :: Any -> Any -> Bool #

(>=) :: Any -> Any -> Bool #

max :: Any -> Any -> Any #

min :: Any -> Any -> Any #

type Rep Any

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

type Rep Any = D1 ('MetaData "Any" "Data.Semigroup.Internal" "base" 'True) (C1 ('MetaCons "Any" 'PrefixI 'True) (S1 ('MetaSel ('Just "getAny") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Bool)))

class Semigroup a where #

The class of semigroups (types with an associative binary operation).

Instances should satisfy the following:

Associativity
x <> (y <> z) = (x <> y) <> z

You can alternatively define sconcat instead of (<>), in which case the laws are:

Unit
sconcat (pure x) = x
Multiplication
sconcat (join xss) = sconcat (fmap sconcat xss)

Since: base-4.9.0.0

Minimal complete definition

(<>) | sconcat

Methods

(<>) :: a -> a -> a infixr 6 #

An associative operation.

>>> [1,2,3] <> [4,5,6]
[1,2,3,4,5,6]

sconcat :: NonEmpty a -> a #

Reduce a non-empty list with <>

The default definition should be sufficient, but this can be overridden for efficiency.

>>> import Data.List.NonEmpty (NonEmpty (..))
>>> sconcat $ "Hello" :| [" ", "Haskell", "!"]
"Hello Haskell!"

stimes :: Integral b => b -> a -> a #

Repeat a value n times.

Given that this works on a Semigroup it is allowed to fail if you request 0 or fewer repetitions, and the default definition will do so.

By making this a member of the class, idempotent semigroups and monoids can upgrade this to execute in \(\mathcal{O}(1)\) by picking stimes = stimesIdempotent or stimes = stimesIdempotentMonoid respectively.

>>> stimes 4 [1]
[1,1,1,1]

Instances

Instances details
Semigroup All

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: All -> All -> All #

sconcat :: NonEmpty All -> All #

stimes :: Integral b => b -> All -> All #

Semigroup Any

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Any -> Any -> Any #

sconcat :: NonEmpty Any -> Any #

stimes :: Integral b => b -> Any -> Any #

Semigroup Void

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: Void -> Void -> Void #

sconcat :: NonEmpty Void -> Void #

stimes :: Integral b => b -> Void -> Void #

Semigroup Ordering

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Semigroup ()

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: () -> () -> () #

sconcat :: NonEmpty () -> () #

stimes :: Integral b => b -> () -> () #

Semigroup a => Semigroup (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Methods

(<>) :: Identity a -> Identity a -> Identity a #

sconcat :: NonEmpty (Identity a) -> Identity a #

stimes :: Integral b => b -> Identity a -> Identity a #

Semigroup (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Monoid

Methods

(<>) :: First a -> First a -> First a #

sconcat :: NonEmpty (First a) -> First a #

stimes :: Integral b => b -> First a -> First a #

Semigroup (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Monoid

Methods

(<>) :: Last a -> Last a -> Last a #

sconcat :: NonEmpty (Last a) -> Last a #

stimes :: Integral b => b -> Last a -> Last a #

Semigroup a => Semigroup (Down a)

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

(<>) :: Down a -> Down a -> Down a #

sconcat :: NonEmpty (Down a) -> Down a #

stimes :: Integral b => b -> Down a -> Down a #

Semigroup (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: First a -> First a -> First a #

sconcat :: NonEmpty (First a) -> First a #

stimes :: Integral b => b -> First a -> First a #

Semigroup (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: Last a -> Last a -> Last a #

sconcat :: NonEmpty (Last a) -> Last a #

stimes :: Integral b => b -> Last a -> Last a #

Ord a => Semigroup (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: Max a -> Max a -> Max a #

sconcat :: NonEmpty (Max a) -> Max a #

stimes :: Integral b => b -> Max a -> Max a #

Ord a => Semigroup (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: Min a -> Min a -> Min a #

sconcat :: NonEmpty (Min a) -> Min a #

stimes :: Integral b => b -> Min a -> Min a #

Monoid m => Semigroup (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Semigroup a => Semigroup (Dual a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Dual a -> Dual a -> Dual a #

sconcat :: NonEmpty (Dual a) -> Dual a #

stimes :: Integral b => b -> Dual a -> Dual a #

Semigroup (Endo a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Endo a -> Endo a -> Endo a #

sconcat :: NonEmpty (Endo a) -> Endo a #

stimes :: Integral b => b -> Endo a -> Endo a #

Num a => Semigroup (Product a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Product a -> Product a -> Product a #

sconcat :: NonEmpty (Product a) -> Product a #

stimes :: Integral b => b -> Product a -> Product a #

Num a => Semigroup (Sum a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Sum a -> Sum a -> Sum a #

sconcat :: NonEmpty (Sum a) -> Sum a #

stimes :: Integral b => b -> Sum a -> Sum a #

Semigroup (NonEmpty a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: NonEmpty a -> NonEmpty a -> NonEmpty a #

sconcat :: NonEmpty (NonEmpty a) -> NonEmpty a #

stimes :: Integral b => b -> NonEmpty a -> NonEmpty a #

(Generic a, Semigroup (Rep a ())) => Semigroup (Generically a)

Since: base-4.17.0.0

Instance details

Defined in GHC.Generics

Semigroup p => Semigroup (Par1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: Par1 p -> Par1 p -> Par1 p #

sconcat :: NonEmpty (Par1 p) -> Par1 p #

stimes :: Integral b => b -> Par1 p -> Par1 p #

Semigroup a => Semigroup (IO a)

Since: base-4.10.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: IO a -> IO a -> IO a #

sconcat :: NonEmpty (IO a) -> IO a #

stimes :: Integral b => b -> IO a -> IO a #

Additive a => Semigroup (Sum a) Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

(<>) :: Sum a -> Sum a -> Sum a #

sconcat :: NonEmpty (Sum a) -> Sum a #

stimes :: Integral b => b -> Sum a -> Sum a #

Multiplicative a => Semigroup (Product a) Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

(<>) :: Product a -> Product a -> Product a #

sconcat :: NonEmpty (Product a) -> Product a #

stimes :: Integral b => b -> Product a -> Product a #

Semigroup a => Semigroup (Maybe a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: Maybe a -> Maybe a -> Maybe a #

sconcat :: NonEmpty (Maybe a) -> Maybe a #

stimes :: Integral b => b -> Maybe a -> Maybe a #

Semigroup a => Semigroup (a)

Since: base-4.15

Instance details

Defined in GHC.Base

Methods

(<>) :: (a) -> (a) -> (a) #

sconcat :: NonEmpty (a) -> (a) #

stimes :: Integral b => b -> (a) -> (a) #

Semigroup [a]

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: [a] -> [a] -> [a] #

sconcat :: NonEmpty [a] -> [a] #

stimes :: Integral b => b -> [a] -> [a] #

Semigroup (Either a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Either

Methods

(<>) :: Either a b -> Either a b -> Either a b #

sconcat :: NonEmpty (Either a b) -> Either a b #

stimes :: Integral b0 => b0 -> Either a b -> Either a b #

Semigroup (U1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: U1 p -> U1 p -> U1 p #

sconcat :: NonEmpty (U1 p) -> U1 p #

stimes :: Integral b => b -> U1 p -> U1 p #

Semigroup (V1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: V1 p -> V1 p -> V1 p #

sconcat :: NonEmpty (V1 p) -> V1 p #

stimes :: Integral b => b -> V1 p -> V1 p #

(Semigroup a, Semigroup b) => Semigroup (a, b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b) -> (a, b) -> (a, b) #

sconcat :: NonEmpty (a, b) -> (a, b) #

stimes :: Integral b0 => b0 -> (a, b) -> (a, b) #

Semigroup b => Semigroup (a -> b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a -> b) -> (a -> b) -> a -> b #

sconcat :: NonEmpty (a -> b) -> a -> b #

stimes :: Integral b0 => b0 -> (a -> b) -> a -> b #

Semigroup a => Semigroup (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

(<>) :: Const a b -> Const a b -> Const a b #

sconcat :: NonEmpty (Const a b) -> Const a b #

stimes :: Integral b0 => b0 -> Const a b -> Const a b #

(Applicative f, Semigroup a) => Semigroup (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

(<>) :: Ap f a -> Ap f a -> Ap f a #

sconcat :: NonEmpty (Ap f a) -> Ap f a #

stimes :: Integral b => b -> Ap f a -> Ap f a #

Alternative f => Semigroup (Alt f a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Alt f a -> Alt f a -> Alt f a #

sconcat :: NonEmpty (Alt f a) -> Alt f a #

stimes :: Integral b => b -> Alt f a -> Alt f a #

Semigroup (f p) => Semigroup (Rec1 f p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: Rec1 f p -> Rec1 f p -> Rec1 f p #

sconcat :: NonEmpty (Rec1 f p) -> Rec1 f p #

stimes :: Integral b => b -> Rec1 f p -> Rec1 f p #

(Semigroup a, Semigroup b, Semigroup c) => Semigroup (a, b, c)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b, c) -> (a, b, c) -> (a, b, c) #

sconcat :: NonEmpty (a, b, c) -> (a, b, c) #

stimes :: Integral b0 => b0 -> (a, b, c) -> (a, b, c) #

(Semigroup (f p), Semigroup (g p)) => Semigroup ((f :*: g) p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: (f :*: g) p -> (f :*: g) p -> (f :*: g) p #

sconcat :: NonEmpty ((f :*: g) p) -> (f :*: g) p #

stimes :: Integral b => b -> (f :*: g) p -> (f :*: g) p #

Semigroup c => Semigroup (K1 i c p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: K1 i c p -> K1 i c p -> K1 i c p #

sconcat :: NonEmpty (K1 i c p) -> K1 i c p #

stimes :: Integral b => b -> K1 i c p -> K1 i c p #

(Semigroup a, Semigroup b, Semigroup c, Semigroup d) => Semigroup (a, b, c, d)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b, c, d) -> (a, b, c, d) -> (a, b, c, d) #

sconcat :: NonEmpty (a, b, c, d) -> (a, b, c, d) #

stimes :: Integral b0 => b0 -> (a, b, c, d) -> (a, b, c, d) #

Semigroup (f (g p)) => Semigroup ((f :.: g) p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: (f :.: g) p -> (f :.: g) p -> (f :.: g) p #

sconcat :: NonEmpty ((f :.: g) p) -> (f :.: g) p #

stimes :: Integral b => b -> (f :.: g) p -> (f :.: g) p #

Semigroup (f p) => Semigroup (M1 i c f p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: M1 i c f p -> M1 i c f p -> M1 i c f p #

sconcat :: NonEmpty (M1 i c f p) -> M1 i c f p #

stimes :: Integral b => b -> M1 i c f p -> M1 i c f p #

(Semigroup a, Semigroup b, Semigroup c, Semigroup d, Semigroup e) => Semigroup (a, b, c, d, e)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b, c, d, e) -> (a, b, c, d, e) -> (a, b, c, d, e) #

sconcat :: NonEmpty (a, b, c, d, e) -> (a, b, c, d, e) #

stimes :: Integral b0 => b0 -> (a, b, c, d, e) -> (a, b, c, d, e) #

newtype Last a #

Beware that Data.Semigroup.Last is different from Data.Monoid.Last. The former simply returns the last value, so x <> Data.Semigroup.Last Nothing = Data.Semigroup.Last Nothing. The latter returns the last non-Nothing, thus x <> Data.Monoid.Last Nothing = x.

Constructors

Last 

Fields

Instances

Instances details
MonadFix Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mfix :: (a -> Last a) -> Last a #

Foldable Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Last m -> m #

foldMap :: Monoid m => (a -> m) -> Last a -> m #

foldMap' :: Monoid m => (a -> m) -> Last a -> m #

foldr :: (a -> b -> b) -> b -> Last a -> b #

foldr' :: (a -> b -> b) -> b -> Last a -> b #

foldl :: (b -> a -> b) -> b -> Last a -> b #

foldl' :: (b -> a -> b) -> b -> Last a -> b #

foldr1 :: (a -> a -> a) -> Last a -> a #

foldl1 :: (a -> a -> a) -> Last a -> a #

toList :: Last a -> [a] #

null :: Last a -> Bool #

length :: Last a -> Int #

elem :: Eq a => a -> Last a -> Bool #

maximum :: Ord a => Last a -> a #

minimum :: Ord a => Last a -> a #

sum :: Num a => Last a -> a #

product :: Num a => Last a -> a #

Traversable Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a -> f b) -> Last a -> f (Last b) #

sequenceA :: Applicative f => Last (f a) -> f (Last a) #

mapM :: Monad m => (a -> m b) -> Last a -> m (Last b) #

sequence :: Monad m => Last (m a) -> m (Last a) #

Applicative Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Last a #

(<*>) :: Last (a -> b) -> Last a -> Last b #

liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c #

(*>) :: Last a -> Last b -> Last b #

(<*) :: Last a -> Last b -> Last a #

Functor Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a -> b) -> Last a -> Last b #

(<$) :: a -> Last b -> Last a #

Monad Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(>>=) :: Last a -> (a -> Last b) -> Last b #

(>>) :: Last a -> Last b -> Last b #

return :: a -> Last a #

Generic1 Last 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep1 Last :: k -> Type #

Methods

from1 :: forall (a :: k). Last a -> Rep1 Last a #

to1 :: forall (a :: k). Rep1 Last a -> Last a #

Data a => Data (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Last a -> c (Last a) #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Last a) #

toConstr :: Last a -> Constr #

dataTypeOf :: Last a -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Last a)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Last a)) #

gmapT :: (forall b. Data b => b -> b) -> Last a -> Last a #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r #

gmapQ :: (forall d. Data d => d -> u) -> Last a -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Last a -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) #

Semigroup (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: Last a -> Last a -> Last a #

sconcat :: NonEmpty (Last a) -> Last a #

stimes :: Integral b => b -> Last a -> Last a #

Bounded a => Bounded (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

minBound :: Last a #

maxBound :: Last a #

Enum a => Enum (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

succ :: Last a -> Last a #

pred :: Last a -> Last a #

toEnum :: Int -> Last a #

fromEnum :: Last a -> Int #

enumFrom :: Last a -> [Last a] #

enumFromThen :: Last a -> Last a -> [Last a] #

enumFromTo :: Last a -> Last a -> [Last a] #

enumFromThenTo :: Last a -> Last a -> Last a -> [Last a] #

Generic (Last a) 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep (Last a) :: Type -> Type #

Methods

from :: Last a -> Rep (Last a) x #

to :: Rep (Last a) x -> Last a #

Read a => Read (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Show a => Show (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> Last a -> ShowS #

show :: Last a -> String #

showList :: [Last a] -> ShowS #

Eq a => Eq (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: Last a -> Last a -> Bool #

(/=) :: Last a -> Last a -> Bool #

Ord a => Ord (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: Last a -> Last a -> Ordering #

(<) :: Last a -> Last a -> Bool #

(<=) :: Last a -> Last a -> Bool #

(>) :: Last a -> Last a -> Bool #

(>=) :: Last a -> Last a -> Bool #

max :: Last a -> Last a -> Last a #

min :: Last a -> Last a -> Last a #

type Rep1 Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep1 Last = D1 ('MetaData "Last" "Data.Semigroup" "base" 'True) (C1 ('MetaCons "Last" 'PrefixI 'True) (S1 ('MetaSel ('Just "getLast") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))
type Rep (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep (Last a) = D1 ('MetaData "Last" "Data.Semigroup" "base" 'True) (C1 ('MetaCons "Last" 'PrefixI 'True) (S1 ('MetaSel ('Just "getLast") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

newtype First a #

Beware that Data.Semigroup.First is different from Data.Monoid.First. The former simply returns the first value, so Data.Semigroup.First Nothing <> x = Data.Semigroup.First Nothing. The latter returns the first non-Nothing, thus Data.Monoid.First Nothing <> x = x.

Constructors

First 

Fields

Instances

Instances details
MonadFix First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mfix :: (a -> First a) -> First a #

Foldable First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => First m -> m #

foldMap :: Monoid m => (a -> m) -> First a -> m #

foldMap' :: Monoid m => (a -> m) -> First a -> m #

foldr :: (a -> b -> b) -> b -> First a -> b #

foldr' :: (a -> b -> b) -> b -> First a -> b #

foldl :: (b -> a -> b) -> b -> First a -> b #

foldl' :: (b -> a -> b) -> b -> First a -> b #

foldr1 :: (a -> a -> a) -> First a -> a #

foldl1 :: (a -> a -> a) -> First a -> a #

toList :: First a -> [a] #

null :: First a -> Bool #

length :: First a -> Int #

elem :: Eq a => a -> First a -> Bool #

maximum :: Ord a => First a -> a #

minimum :: Ord a => First a -> a #

sum :: Num a => First a -> a #

product :: Num a => First a -> a #

Traversable First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a -> f b) -> First a -> f (First b) #

sequenceA :: Applicative f => First (f a) -> f (First a) #

mapM :: Monad m => (a -> m b) -> First a -> m (First b) #

sequence :: Monad m => First (m a) -> m (First a) #

Applicative First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> First a #

(<*>) :: First (a -> b) -> First a -> First b #

liftA2 :: (a -> b -> c) -> First a -> First b -> First c #

(*>) :: First a -> First b -> First b #

(<*) :: First a -> First b -> First a #

Functor First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a -> b) -> First a -> First b #

(<$) :: a -> First b -> First a #

Monad First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(>>=) :: First a -> (a -> First b) -> First b #

(>>) :: First a -> First b -> First b #

return :: a -> First a #

Generic1 First 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep1 First :: k -> Type #

Methods

from1 :: forall (a :: k). First a -> Rep1 First a #

to1 :: forall (a :: k). Rep1 First a -> First a #

Data a => Data (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> First a -> c (First a) #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (First a) #

toConstr :: First a -> Constr #

dataTypeOf :: First a -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (First a)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (First a)) #

gmapT :: (forall b. Data b => b -> b) -> First a -> First a #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r #

gmapQ :: (forall d. Data d => d -> u) -> First a -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> First a -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> First a -> m (First a) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) #

Semigroup (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: First a -> First a -> First a #

sconcat :: NonEmpty (First a) -> First a #

stimes :: Integral b => b -> First a -> First a #

Bounded a => Bounded (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

minBound :: First a #

maxBound :: First a #

Enum a => Enum (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

succ :: First a -> First a #

pred :: First a -> First a #

toEnum :: Int -> First a #

fromEnum :: First a -> Int #

enumFrom :: First a -> [First a] #

enumFromThen :: First a -> First a -> [First a] #

enumFromTo :: First a -> First a -> [First a] #

enumFromThenTo :: First a -> First a -> First a -> [First a] #

Generic (First a) 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep (First a) :: Type -> Type #

Methods

from :: First a -> Rep (First a) x #

to :: Rep (First a) x -> First a #

Read a => Read (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Show a => Show (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> First a -> ShowS #

show :: First a -> String #

showList :: [First a] -> ShowS #

Eq a => Eq (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: First a -> First a -> Bool #

(/=) :: First a -> First a -> Bool #

Ord a => Ord (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: First a -> First a -> Ordering #

(<) :: First a -> First a -> Bool #

(<=) :: First a -> First a -> Bool #

(>) :: First a -> First a -> Bool #

(>=) :: First a -> First a -> Bool #

max :: First a -> First a -> First a #

min :: First a -> First a -> First a #

type Rep1 First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep1 First = D1 ('MetaData "First" "Data.Semigroup" "base" 'True) (C1 ('MetaCons "First" 'PrefixI 'True) (S1 ('MetaSel ('Just "getFirst") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))
type Rep (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep (First a) = D1 ('MetaData "First" "Data.Semigroup" "base" 'True) (C1 ('MetaCons "First" 'PrefixI 'True) (S1 ('MetaSel ('Just "getFirst") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

newtype All #

Boolean monoid under conjunction (&&).

>>> getAll (All True <> mempty <> All False)
False
>>> getAll (mconcat (map (\x -> All (even x)) [2,4,6,7,8]))
False

Constructors

All 

Fields

Instances

Instances details
Data All

Since: base-4.8.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> All -> c All #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c All #

toConstr :: All -> Constr #

dataTypeOf :: All -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c All) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c All) #

gmapT :: (forall b. Data b => b -> b) -> All -> All #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> All -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> All -> r #

gmapQ :: (forall d. Data d => d -> u) -> All -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> All -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> All -> m All #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All #

Monoid All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: All #

mappend :: All -> All -> All #

mconcat :: [All] -> All #

Semigroup All

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: All -> All -> All #

sconcat :: NonEmpty All -> All #

stimes :: Integral b => b -> All -> All #

Bounded All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

minBound :: All #

maxBound :: All #

Generic All 
Instance details

Defined in Data.Semigroup.Internal

Associated Types

type Rep All :: Type -> Type #

Methods

from :: All -> Rep All x #

to :: Rep All x -> All #

Read All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Show All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> All -> ShowS #

show :: All -> String #

showList :: [All] -> ShowS #

Eq All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: All -> All -> Bool #

(/=) :: All -> All -> Bool #

Ord All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: All -> All -> Ordering #

(<) :: All -> All -> Bool #

(<=) :: All -> All -> Bool #

(>) :: All -> All -> Bool #

(>=) :: All -> All -> Bool #

max :: All -> All -> All #

min :: All -> All -> All #

type Rep All

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

type Rep All = D1 ('MetaData "All" "Data.Semigroup.Internal" "base" 'True) (C1 ('MetaCons "All" 'PrefixI 'True) (S1 ('MetaSel ('Just "getAll") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Bool)))

newtype Endo a #

The monoid of endomorphisms under composition.

>>> let computation = Endo ("Hello, " ++) <> Endo (++ "!")
>>> appEndo computation "Haskell"
"Hello, Haskell!"

Constructors

Endo 

Fields

Instances

Instances details
Monoid (Endo a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Endo a #

mappend :: Endo a -> Endo a -> Endo a #

mconcat :: [Endo a] -> Endo a #

Semigroup (Endo a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Endo a -> Endo a -> Endo a #

sconcat :: NonEmpty (Endo a) -> Endo a #

stimes :: Integral b => b -> Endo a -> Endo a #

Generic (Endo a) 
Instance details

Defined in Data.Semigroup.Internal

Associated Types

type Rep (Endo a) :: Type -> Type #

Methods

from :: Endo a -> Rep (Endo a) x #

to :: Rep (Endo a) x -> Endo a #

type Rep (Endo a)

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

type Rep (Endo a) = D1 ('MetaData "Endo" "Data.Semigroup.Internal" "base" 'True) (C1 ('MetaCons "Endo" 'PrefixI 'True) (S1 ('MetaSel ('Just "appEndo") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (a -> a))))

newtype Dual a #

The dual of a Monoid, obtained by swapping the arguments of mappend.

>>> getDual (mappend (Dual "Hello") (Dual "World"))
"WorldHello"

Constructors

Dual 

Fields

Instances

Instances details
Foldable Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Dual m -> m #

foldMap :: Monoid m => (a -> m) -> Dual a -> m #

foldMap' :: Monoid m => (a -> m) -> Dual a -> m #

foldr :: (a -> b -> b) -> b -> Dual a -> b #

foldr' :: (a -> b -> b) -> b -> Dual a -> b #

foldl :: (b -> a -> b) -> b -> Dual a -> b #

foldl' :: (b -> a -> b) -> b -> Dual a -> b #

foldr1 :: (a -> a -> a) -> Dual a -> a #

foldl1 :: (a -> a -> a) -> Dual a -> a #

toList :: Dual a -> [a] #

null :: Dual a -> Bool #

length :: Dual a -> Int #

elem :: Eq a => a -> Dual a -> Bool #

maximum :: Ord a => Dual a -> a #

minimum :: Ord a => Dual a -> a #

sum :: Num a => Dual a -> a #

product :: Num a => Dual a -> a #

Traversable Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Dual a -> f (Dual b) #

sequenceA :: Applicative f => Dual (f a) -> f (Dual a) #

mapM :: Monad m => (a -> m b) -> Dual a -> m (Dual b) #

sequence :: Monad m => Dual (m a) -> m (Dual a) #

Applicative Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Dual a #

(<*>) :: Dual (a -> b) -> Dual a -> Dual b #

liftA2 :: (a -> b -> c) -> Dual a -> Dual b -> Dual c #

(*>) :: Dual a -> Dual b -> Dual b #

(<*) :: Dual a -> Dual b -> Dual a #

Functor Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

fmap :: (a -> b) -> Dual a -> Dual b #

(<$) :: a -> Dual b -> Dual a #

Monad Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(>>=) :: Dual a -> (a -> Dual b) -> Dual b #

(>>) :: Dual a -> Dual b -> Dual b #

return :: a -> Dual a #

Generic1 Dual 
Instance details

Defined in Data.Semigroup.Internal

Associated Types

type Rep1 Dual :: k -> Type #

Methods

from1 :: forall (a :: k). Dual a -> Rep1 Dual a #

to1 :: forall (a :: k). Rep1 Dual a -> Dual a #

Data a => Data (Dual a)

Since: base-4.8.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Dual a -> c (Dual a) #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Dual a) #

toConstr :: Dual a -> Constr #

dataTypeOf :: Dual a -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Dual a)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Dual a)) #

gmapT :: (forall b. Data b => b -> b) -> Dual a -> Dual a #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r #

gmapQ :: (forall d. Data d => d -> u) -> Dual a -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Dual a -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) #

Monoid a => Monoid (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Dual a #

mappend :: Dual a -> Dual a -> Dual a #

mconcat :: [Dual a] -> Dual a #

Semigroup a => Semigroup (Dual a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Dual a -> Dual a -> Dual a #

sconcat :: NonEmpty (Dual a) -> Dual a #

stimes :: Integral b => b -> Dual a -> Dual a #

Bounded a => Bounded (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

minBound :: Dual a #

maxBound :: Dual a #

Generic (Dual a) 
Instance details

Defined in Data.Semigroup.Internal

Associated Types

type Rep (Dual a) :: Type -> Type #

Methods

from :: Dual a -> Rep (Dual a) x #

to :: Rep (Dual a) x -> Dual a #

Read a => Read (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Show a => Show (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> Dual a -> ShowS #

show :: Dual a -> String #

showList :: [Dual a] -> ShowS #

Eq a => Eq (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: Dual a -> Dual a -> Bool #

(/=) :: Dual a -> Dual a -> Bool #

Ord a => Ord (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: Dual a -> Dual a -> Ordering #

(<) :: Dual a -> Dual a -> Bool #

(<=) :: Dual a -> Dual a -> Bool #

(>) :: Dual a -> Dual a -> Bool #

(>=) :: Dual a -> Dual a -> Bool #

max :: Dual a -> Dual a -> Dual a #

min :: Dual a -> Dual a -> Dual a #

type Rep1 Dual

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

type Rep1 Dual = D1 ('MetaData "Dual" "Data.Semigroup.Internal" "base" 'True) (C1 ('MetaCons "Dual" 'PrefixI 'True) (S1 ('MetaSel ('Just "getDual") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))
type Rep (Dual a)

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

type Rep (Dual a) = D1 ('MetaData "Dual" "Data.Semigroup.Internal" "base" 'True) (C1 ('MetaCons "Dual" 'PrefixI 'True) (S1 ('MetaSel ('Just "getDual") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

newtype WrappedMonoid m #

Provide a Semigroup for an arbitrary Monoid.

NOTE: This is not needed anymore since Semigroup became a superclass of Monoid in base-4.11 and this newtype be deprecated at some point in the future.

Constructors

WrapMonoid 

Fields

Instances

Instances details
Generic1 WrappedMonoid 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep1 WrappedMonoid :: k -> Type #

Methods

from1 :: forall (a :: k). WrappedMonoid a -> Rep1 WrappedMonoid a #

to1 :: forall (a :: k). Rep1 WrappedMonoid a -> WrappedMonoid a #

Data m => Data (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> WrappedMonoid m -> c (WrappedMonoid m) #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (WrappedMonoid m) #

toConstr :: WrappedMonoid m -> Constr #

dataTypeOf :: WrappedMonoid m -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (WrappedMonoid m)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (WrappedMonoid m)) #

gmapT :: (forall b. Data b => b -> b) -> WrappedMonoid m -> WrappedMonoid m #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> WrappedMonoid m -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> WrappedMonoid m -> r #

gmapQ :: (forall d. Data d => d -> u) -> WrappedMonoid m -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> WrappedMonoid m -> u #

gmapM :: Monad m0 => (forall d. Data d => d -> m0 d) -> WrappedMonoid m -> m0 (WrappedMonoid m) #

gmapMp :: MonadPlus m0 => (forall d. Data d => d -> m0 d) -> WrappedMonoid m -> m0 (WrappedMonoid m) #

gmapMo :: MonadPlus m0 => (forall d. Data d => d -> m0 d) -> WrappedMonoid m -> m0 (WrappedMonoid m) #

Monoid m => Monoid (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Monoid m => Semigroup (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Bounded m => Bounded (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Enum a => Enum (WrappedMonoid a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Generic (WrappedMonoid m) 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep (WrappedMonoid m) :: Type -> Type #

Read m => Read (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Show m => Show (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Eq m => Eq (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Ord m => Ord (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep1 WrappedMonoid

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep1 WrappedMonoid = D1 ('MetaData "WrappedMonoid" "Data.Semigroup" "base" 'True) (C1 ('MetaCons "WrapMonoid" 'PrefixI 'True) (S1 ('MetaSel ('Just "unwrapMonoid") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))
type Rep (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep (WrappedMonoid m) = D1 ('MetaData "WrappedMonoid" "Data.Semigroup" "base" 'True) (C1 ('MetaCons "WrapMonoid" 'PrefixI 'True) (S1 ('MetaSel ('Just "unwrapMonoid") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 m)))

type ArgMax a b = Max (Arg a b) #

>>> Max (Arg 0 ()) <> Max (Arg 1 ())
Max {getMax = Arg 1 ()}

type ArgMin a b = Min (Arg a b) #

>>> Min (Arg 0 ()) <> Min (Arg 1 ())
Min {getMin = Arg 0 ()}

data Arg a b #

Arg isn't itself a Semigroup in its own right, but it can be placed inside Min and Max to compute an arg min or arg max.

>>> minimum [ Arg (x * x) x | x <- [-10 .. 10] ]
Arg 0 0

Constructors

Arg 

Fields

  • a

    The argument used for comparisons in Eq and Ord.

  • b

    The "value" exposed via the Functor, Foldable etc. instances.

Instances

Instances details
Bifoldable Arg

Since: base-4.10.0.0

Instance details

Defined in Data.Semigroup

Methods

bifold :: Monoid m => Arg m m -> m #

bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> Arg a b -> m #

bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> Arg a b -> c #

bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> Arg a b -> c #

Bifunctor Arg

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

bimap :: (a -> b) -> (c -> d) -> Arg a c -> Arg b d #

first :: (a -> b) -> Arg a c -> Arg b c #

second :: (b -> c) -> Arg a b -> Arg a c #

Bitraversable Arg

Since: base-4.10.0.0

Instance details

Defined in Data.Semigroup

Methods

bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Arg a b -> f (Arg c d) #

Generic1 (Arg a :: Type -> Type) 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep1 (Arg a) :: k -> Type #

Methods

from1 :: forall (a0 :: k). Arg a a0 -> Rep1 (Arg a) a0 #

to1 :: forall (a0 :: k). Rep1 (Arg a) a0 -> Arg a a0 #

Foldable (Arg a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Arg a m -> m #

foldMap :: Monoid m => (a0 -> m) -> Arg a a0 -> m #

foldMap' :: Monoid m => (a0 -> m) -> Arg a a0 -> m #

foldr :: (a0 -> b -> b) -> b -> Arg a a0 -> b #

foldr' :: (a0 -> b -> b) -> b -> Arg a a0 -> b #

foldl :: (b -> a0 -> b) -> b -> Arg a a0 -> b #

foldl' :: (b -> a0 -> b) -> b -> Arg a a0 -> b #

foldr1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 #

toList :: Arg a a0 -> [a0] #

null :: Arg a a0 -> Bool #

length :: Arg a a0 -> Int #

elem :: Eq a0 => a0 -> Arg a a0 -> Bool #

maximum :: Ord a0 => Arg a a0 -> a0 #

minimum :: Ord a0 => Arg a a0 -> a0 #

sum :: Num a0 => Arg a a0 -> a0 #

product :: Num a0 => Arg a a0 -> a0 #

Traversable (Arg a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a0 -> f b) -> Arg a a0 -> f (Arg a b) #

sequenceA :: Applicative f => Arg a (f a0) -> f (Arg a a0) #

mapM :: Monad m => (a0 -> m b) -> Arg a a0 -> m (Arg a b) #

sequence :: Monad m => Arg a (m a0) -> m (Arg a a0) #

Functor (Arg a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a0 -> b) -> Arg a a0 -> Arg a b #

(<$) :: a0 -> Arg a b -> Arg a a0 #

(Data a, Data b) => Data (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Arg a b -> c (Arg a b) #

gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Arg a b) #

toConstr :: Arg a b -> Constr #

dataTypeOf :: Arg a b -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Arg a b)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Arg a b)) #

gmapT :: (forall b0. Data b0 => b0 -> b0) -> Arg a b -> Arg a b #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r #

gmapQ :: (forall d. Data d => d -> u) -> Arg a b -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Arg a b -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) #

Generic (Arg a b) 
Instance details

Defined in Data.Semigroup

Associated Types

type Rep (Arg a b) :: Type -> Type #

Methods

from :: Arg a b -> Rep (Arg a b) x #

to :: Rep (Arg a b) x -> Arg a b #

(Read a, Read b) => Read (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

readsPrec :: Int -> ReadS (Arg a b) #

readList :: ReadS [Arg a b] #

readPrec :: ReadPrec (Arg a b) #

readListPrec :: ReadPrec [Arg a b] #

(Show a, Show b) => Show (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> Arg a b -> ShowS #

show :: Arg a b -> String #

showList :: [Arg a b] -> ShowS #

Eq a => Eq (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: Arg a b -> Arg a b -> Bool #

(/=) :: Arg a b -> Arg a b -> Bool #

Ord a => Ord (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: Arg a b -> Arg a b -> Ordering #

(<) :: Arg a b -> Arg a b -> Bool #

(<=) :: Arg a b -> Arg a b -> Bool #

(>) :: Arg a b -> Arg a b -> Bool #

(>=) :: Arg a b -> Arg a b -> Bool #

max :: Arg a b -> Arg a b -> Arg a b #

min :: Arg a b -> Arg a b -> Arg a b #

type Rep1 (Arg a :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

type Rep (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

stimesIdempotent :: Integral b => b -> a -> a #

This is a valid definition of stimes for an idempotent Semigroup.

When x <> x = x, this definition should be preferred, because it works in \(\mathcal{O}(1)\) rather than \(\mathcal{O}(\log n)\).

stimesIdempotentMonoid :: (Integral b, Monoid a) => b -> a -> a #

This is a valid definition of stimes for an idempotent Monoid.

When mappend x x = x, this definition should be preferred, because it works in \(\mathcal{O}(1)\) rather than \(\mathcal{O}(\log n)\)

stimesMonoid :: (Integral b, Monoid a) => b -> a -> a #

This is a valid definition of stimes for a Monoid.

Unlike the default definition of stimes, it is defined for 0 and so it should be preferred where possible.

cycle1 :: Semigroup m => m -> m #

A generalization of cycle to an arbitrary Semigroup. May fail to terminate for some values in some semigroups.

diff :: Semigroup m => m -> Endo m #

This lets you use a difference list of a Semigroup as a Monoid.

Example:

Expand
>>> let hello = diff "Hello, "
>>> appEndo hello "World!"
"Hello, World!"
>>> appEndo (hello <> mempty) "World!"
"Hello, World!"
>>> appEndo (mempty <> hello) "World!"
"Hello, World!"
>>> let world = diff "World"
>>> let excl = diff "!"
>>> appEndo (hello <> (world <> excl)) mempty
"Hello, World!"
>>> appEndo ((hello <> world) <> excl) mempty
"Hello, World!"

mtimesDefault :: (Integral b, Monoid a) => b -> a -> a #

Repeat a value n times.

mtimesDefault n a = a <> a <> ... <> a  -- using <> (n-1) times

In many cases, `stimes 0 a` for a Monoid will produce mempty. However, there are situations when it cannot do so. In particular, the following situation is fairly common:

data T a = ...

class Constraint1 a
class Constraint1 a => Constraint2 a

instance Constraint1 a => Semigroup (T a) instance Constraint2 a => Monoid (T a) @

Since Constraint1 is insufficient to implement mempty, stimes for T a cannot do so.

When working with such a type, or when working polymorphically with Semigroup instances, mtimesDefault should be used when the multiplier might be zero. It is implemented using stimes when the multiplier is nonzero and mempty when it is zero.

module Data.Maybe

Data.Function

($) :: forall (r :: RuntimeRep) a (b :: TYPE r). (a -> b) -> a -> b infixr 0 #

Application operator. This operator is redundant, since ordinary application (f x) means the same as (f $ x). However, $ has low, right-associative binding precedence, so it sometimes allows parentheses to be omitted; for example:

f $ g $ h x  =  f (g (h x))

It is also useful in higher-order situations, such as map ($ 0) xs, or zipWith ($) fs xs.

Note that ($) is representation-polymorphic in its result type, so that foo $ True where foo :: Bool -> Int# is well-typed.

const :: a -> b -> a #

const x y always evaluates to x, ignoring its second argument.

>>> const 42 "hello"
42
>>> map (const 42) [0..3]
[42,42,42,42]

flip :: (a -> b -> c) -> b -> a -> c #

flip f takes its (first) two arguments in the reverse order of f.

>>> flip (++) "hello" "world"
"worldhello"

fix :: (a -> a) -> a #

fix f is the least fixed point of the function f, i.e. the least defined x such that f x = x.

For example, we can write the factorial function using direct recursion as

>>> let fac n = if n <= 1 then 1 else n * fac (n-1) in fac 5
120

This uses the fact that Haskell’s let introduces recursive bindings. We can rewrite this definition using fix,

>>> fix (\rec n -> if n <= 1 then 1 else n * rec (n-1)) 5
120

Instead of making a recursive call, we introduce a dummy parameter rec; when used within fix, this parameter then refers to fix’s argument, hence the recursion is reintroduced.

on :: (b -> b -> c) -> (a -> b) -> a -> a -> c infixl 0 #

on b u x y runs the binary function b on the results of applying unary function u to two arguments x and y. From the opposite perspective, it transforms two inputs and combines the outputs.

((+) `on` f) x y = f x + f y

Typical usage: sortBy (compare `on` fst).

Algebraic properties:

  • (*) `on` id = (*) -- (if (*) ∉ {⊥, const ⊥})
  • ((*) `on` f) `on` g = (*) `on` (f . g)
  • flip on f . flip on g = flip on (g . f)

(&) :: a -> (a -> b) -> b infixl 1 #

& is a reverse application operator. This provides notational convenience. Its precedence is one higher than that of the forward application operator $, which allows & to be nested in $.

>>> 5 & (+1) & show
"6"

Since: base-4.8.0.0

applyWhen :: Bool -> (a -> a) -> a -> a #

applyWhen applies a function to a value if a condition is true, otherwise, it returns the value unchanged.

It is equivalent to flip (bool id).

Algebraic properties:

Since: base-4.18.0.0

Control.Category

Data.Foldable

class Foldable (t :: Type -> Type) where #

The Foldable class represents data structures that can be reduced to a summary value one element at a time. Strict left-associative folds are a good fit for space-efficient reduction, while lazy right-associative folds are a good fit for corecursive iteration, or for folds that short-circuit after processing an initial subsequence of the structure's elements.

Instances can be derived automatically by enabling the DeriveFoldable extension. For example, a derived instance for a binary tree might be:

{-# LANGUAGE DeriveFoldable #-}
data Tree a = Empty
            | Leaf a
            | Node (Tree a) a (Tree a)
    deriving Foldable

A more detailed description can be found in the Overview section of Data.Foldable.

For the class laws see the Laws section of Data.Foldable.

Minimal complete definition

foldMap | foldr

Methods

fold :: Monoid m => t m -> m #

Given a structure with elements whose type is a Monoid, combine them via the monoid's (<>) operator. This fold is right-associative and lazy in the accumulator. When you need a strict left-associative fold, use foldMap' instead, with id as the map.

Examples

Expand

Basic usage:

>>> fold [[1, 2, 3], [4, 5], [6], []]
[1,2,3,4,5,6]
>>> fold $ Node (Leaf (Sum 1)) (Sum 3) (Leaf (Sum 5))
Sum {getSum = 9}

Folds of unbounded structures do not terminate when the monoid's (<>) operator is strict:

>>> fold (repeat Nothing)
* Hangs forever *

Lazy corecursive folds of unbounded structures are fine:

>>> take 12 $ fold $ map (\i -> [i..i+2]) [0..]
[0,1,2,1,2,3,2,3,4,3,4,5]
>>> sum $ take 4000000 $ fold $ map (\i -> [i..i+2]) [0..]
2666668666666

foldMap :: Monoid m => (a -> m) -> t a -> m #

Map each element of the structure into a monoid, and combine the results with (<>). This fold is right-associative and lazy in the accumulator. For strict left-associative folds consider foldMap' instead.

Examples

Expand

Basic usage:

>>> foldMap Sum [1, 3, 5]
Sum {getSum = 9}
>>> foldMap Product [1, 3, 5]
Product {getProduct = 15}
>>> foldMap (replicate 3) [1, 2, 3]
[1,1,1,2,2,2,3,3,3]

When a Monoid's (<>) is lazy in its second argument, foldMap can return a result even from an unbounded structure. For example, lazy accumulation enables Data.ByteString.Builder to efficiently serialise large data structures and produce the output incrementally:

>>> import qualified Data.ByteString.Lazy as L
>>> import qualified Data.ByteString.Builder as B
>>> let bld :: Int -> B.Builder; bld i = B.intDec i <> B.word8 0x20
>>> let lbs = B.toLazyByteString $ foldMap bld [0..]
>>> L.take 64 lbs
"0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24"

foldMap' :: Monoid m => (a -> m) -> t a -> m #

A left-associative variant of foldMap that is strict in the accumulator. Use this method for strict reduction when partial results are merged via (<>).

Examples

Expand

Define a Monoid over finite bit strings under xor. Use it to strictly compute the xor of a list of Int values.

>>> :set -XGeneralizedNewtypeDeriving
>>> import Data.Bits (Bits, FiniteBits, xor, zeroBits)
>>> import Data.Foldable (foldMap')
>>> import Numeric (showHex)
>>> 
>>> newtype X a = X a deriving (Eq, Bounded, Enum, Bits, FiniteBits)
>>> instance Bits a => Semigroup (X a) where X a <> X b = X (a `xor` b)
>>> instance Bits a => Monoid    (X a) where mempty     = X zeroBits
>>> 
>>> let bits :: [Int]; bits = [0xcafe, 0xfeed, 0xdeaf, 0xbeef, 0x5411]
>>> (\ (X a) -> showString "0x" . showHex a $ "") $ foldMap' X bits
"0x42"

Since: base-4.13.0.0

foldr :: (a -> b -> b) -> b -> t a -> b #

Right-associative fold of a structure, lazy in the accumulator.

In the case of lists, foldr, when applied to a binary operator, a starting value (typically the right-identity of the operator), and a list, reduces the list using the binary operator, from right to left:

foldr f z [x1, x2, ..., xn] == x1 `f` (x2 `f` ... (xn `f` z)...)

Note that since the head of the resulting expression is produced by an application of the operator to the first element of the list, given an operator lazy in its right argument, foldr can produce a terminating expression from an unbounded list.

For a general Foldable structure this should be semantically identical to,

foldr f z = foldr f z . toList

Examples

Expand

Basic usage:

>>> foldr (||) False [False, True, False]
True
>>> foldr (||) False []
False
>>> foldr (\c acc -> acc ++ [c]) "foo" ['a', 'b', 'c', 'd']
"foodcba"
Infinite structures

⚠️ Applying foldr to infinite structures usually doesn't terminate.

It may still terminate under one of the following conditions:

  • the folding function is short-circuiting
  • the folding function is lazy on its second argument
Short-circuiting

(||) short-circuits on True values, so the following terminates because there is a True value finitely far from the left side:

>>> foldr (||) False (True : repeat False)
True

But the following doesn't terminate:

>>> foldr (||) False (repeat False ++ [True])
* Hangs forever *
Laziness in the second argument

Applying foldr to infinite structures terminates when the operator is lazy in its second argument (the initial accumulator is never used in this case, and so could be left undefined, but [] is more clear):

>>> take 5 $ foldr (\i acc -> i : fmap (+3) acc) [] (repeat 1)
[1,4,7,10,13]

foldr' :: (a -> b -> b) -> b -> t a -> b #

foldr' is a variant of foldr that performs strict reduction from right to left, i.e. starting with the right-most element. The input structure must be finite, otherwise foldr' runs out of space (diverges).

If you want a strict right fold in constant space, you need a structure that supports faster than O(n) access to the right-most element, such as Seq from the containers package.

This method does not run in constant space for structures such as lists that don't support efficient right-to-left iteration and so require O(n) space to perform right-to-left reduction. Use of this method with such a structure is a hint that the chosen structure may be a poor fit for the task at hand. If the order in which the elements are combined is not important, use foldl' instead.

Since: base-4.6.0.0

foldl :: (b -> a -> b) -> b -> t a -> b #

Left-associative fold of a structure, lazy in the accumulator. This is rarely what you want, but can work well for structures with efficient right-to-left sequencing and an operator that is lazy in its left argument.

In the case of lists, foldl, when applied to a binary operator, a starting value (typically the left-identity of the operator), and a list, reduces the list using the binary operator, from left to right:

foldl f z [x1, x2, ..., xn] == (...((z `f` x1) `f` x2) `f`...) `f` xn

Note that to produce the outermost application of the operator the entire input list must be traversed. Like all left-associative folds, foldl will diverge if given an infinite list.

If you want an efficient strict left-fold, you probably want to use foldl' instead of foldl. The reason for this is that the latter does not force the inner results (e.g. z `f` x1 in the above example) before applying them to the operator (e.g. to (`f` x2)). This results in a thunk chain O(n) elements long, which then must be evaluated from the outside-in.

For a general Foldable structure this should be semantically identical to:

foldl f z = foldl f z . toList

Examples

Expand

The first example is a strict fold, which in practice is best performed with foldl'.

>>> foldl (+) 42 [1,2,3,4]
52

Though the result below is lazy, the input is reversed before prepending it to the initial accumulator, so corecursion begins only after traversing the entire input string.

>>> foldl (\acc c -> c : acc) "abcd" "efgh"
"hgfeabcd"

A left fold of a structure that is infinite on the right cannot terminate, even when for any finite input the fold just returns the initial accumulator:

>>> foldl (\a _ -> a) 0 $ repeat 1
* Hangs forever *

WARNING: When it comes to lists, you always want to use either foldl' or foldr instead.

foldl' :: (b -> a -> b) -> b -> t a -> b #

Left-associative fold of a structure but with strict application of the operator.

This ensures that each step of the fold is forced to Weak Head Normal Form before being applied, avoiding the collection of thunks that would otherwise occur. This is often what you want to strictly reduce a finite structure to a single strict result (e.g. sum).

For a general Foldable structure this should be semantically identical to,

foldl' f z = foldl' f z . toList

Since: base-4.6.0.0

foldr1 :: (a -> a -> a) -> t a -> a #

A variant of foldr that has no base case, and thus may only be applied to non-empty structures.

This function is non-total and will raise a runtime exception if the structure happens to be empty.

Examples

Expand

Basic usage:

>>> foldr1 (+) [1..4]
10
>>> foldr1 (+) []
Exception: Prelude.foldr1: empty list
>>> foldr1 (+) Nothing
*** Exception: foldr1: empty structure
>>> foldr1 (-) [1..4]
-2
>>> foldr1 (&&) [True, False, True, True]
False
>>> foldr1 (||) [False, False, True, True]
True
>>> foldr1 (+) [1..]
* Hangs forever *

foldl1 :: (a -> a -> a) -> t a -> a #

A variant of foldl that has no base case, and thus may only be applied to non-empty structures.

This function is non-total and will raise a runtime exception if the structure happens to be empty.

foldl1 f = foldl1 f . toList

Examples

Expand

Basic usage:

>>> foldl1 (+) [1..4]
10
>>> foldl1 (+) []
*** Exception: Prelude.foldl1: empty list
>>> foldl1 (+) Nothing
*** Exception: foldl1: empty structure
>>> foldl1 (-) [1..4]
-8
>>> foldl1 (&&) [True, False, True, True]
False
>>> foldl1 (||) [False, False, True, True]
True
>>> foldl1 (+) [1..]
* Hangs forever *

toList :: t a -> [a] #

List of elements of a structure, from left to right. If the entire list is intended to be reduced via a fold, just fold the structure directly bypassing the list.

Examples

Expand

Basic usage:

>>> toList Nothing
[]
>>> toList (Just 42)
[42]
>>> toList (Left "foo")
[]
>>> toList (Node (Leaf 5) 17 (Node Empty 12 (Leaf 8)))
[5,17,12,8]

For lists, toList is the identity:

>>> toList [1, 2, 3]
[1,2,3]

Since: base-4.8.0.0

null :: t a -> Bool #

Test whether the structure is empty. The default implementation is Left-associative and lazy in both the initial element and the accumulator. Thus optimised for structures where the first element can be accessed in constant time. Structures where this is not the case should have a non-default implementation.

Examples

Expand

Basic usage:

>>> null []
True
>>> null [1]
False

null is expected to terminate even for infinite structures. The default implementation terminates provided the structure is bounded on the left (there is a leftmost element).

>>> null [1..]
False

Since: base-4.8.0.0

length :: t a -> Int #

Returns the size/length of a finite structure as an Int. The default implementation just counts elements starting with the leftmost. Instances for structures that can compute the element count faster than via element-by-element counting, should provide a specialised implementation.

Examples

Expand

Basic usage:

>>> length []
0
>>> length ['a', 'b', 'c']
3
>>> length [1..]
* Hangs forever *

Since: base-4.8.0.0

elem :: Eq a => a -> t a -> Bool infix 4 #

Does the element occur in the structure?

Note: elem is often used in infix form.

Examples

Expand

Basic usage:

>>> 3 `elem` []
False
>>> 3 `elem` [1,2]
False
>>> 3 `elem` [1,2,3,4,5]
True

For infinite structures, the default implementation of elem terminates if the sought-after value exists at a finite distance from the left side of the structure:

>>> 3 `elem` [1..]
True
>>> 3 `elem` ([4..] ++ [3])
* Hangs forever *

Since: base-4.8.0.0

maximum :: Ord a => t a -> a #

The largest element of a non-empty structure.

This function is non-total and will raise a runtime exception if the structure happens to be empty. A structure that supports random access and maintains its elements in order should provide a specialised implementation to return the maximum in faster than linear time.

Examples

Expand

Basic usage:

>>> maximum [1..10]
10
>>> maximum []
*** Exception: Prelude.maximum: empty list
>>> maximum Nothing
*** Exception: maximum: empty structure

WARNING: This function is partial for possibly-empty structures like lists.

Since: base-4.8.0.0

minimum :: Ord a => t a -> a #

The least element of a non-empty structure.

This function is non-total and will raise a runtime exception if the structure happens to be empty. A structure that supports random access and maintains its elements in order should provide a specialised implementation to return the minimum in faster than linear time.

Examples

Expand

Basic usage:

>>> minimum [1..10]
1
>>> minimum []
*** Exception: Prelude.minimum: empty list
>>> minimum Nothing
*** Exception: minimum: empty structure

WARNING: This function is partial for possibly-empty structures like lists.

Since: base-4.8.0.0

Instances

Instances details
Foldable ZipList

Since: base-4.9.0.0

Instance details

Defined in Control.Applicative

Methods

fold :: Monoid m => ZipList m -> m #

foldMap :: Monoid m => (a -> m) -> ZipList a -> m #

foldMap' :: Monoid m => (a -> m) -> ZipList a -> m #

foldr :: (a -> b -> b) -> b -> ZipList a -> b #

foldr' :: (a -> b -> b) -> b -> ZipList a -> b #

foldl :: (b -> a -> b) -> b -> ZipList a -> b #

foldl' :: (b -> a -> b) -> b -> ZipList a -> b #

foldr1 :: (a -> a -> a) -> ZipList a -> a #

foldl1 :: (a -> a -> a) -> ZipList a -> a #

toList :: ZipList a -> [a] #

null :: ZipList a -> Bool #

length :: ZipList a -> Int #

elem :: Eq a => a -> ZipList a -> Bool #

maximum :: Ord a => ZipList a -> a #

minimum :: Ord a => ZipList a -> a #

sum :: Num a => ZipList a -> a #

product :: Num a => ZipList a -> a #

Foldable Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

fold :: Monoid m => Identity m -> m #

foldMap :: Monoid m => (a -> m) -> Identity a -> m #

foldMap' :: Monoid m => (a -> m) -> Identity a -> m #

foldr :: (a -> b -> b) -> b -> Identity a -> b #

foldr' :: (a -> b -> b) -> b -> Identity a -> b #

foldl :: (b -> a -> b) -> b -> Identity a -> b #

foldl' :: (b -> a -> b) -> b -> Identity a -> b #

foldr1 :: (a -> a -> a) -> Identity a -> a #

foldl1 :: (a -> a -> a) -> Identity a -> a #

toList :: Identity a -> [a] #

null :: Identity a -> Bool #

length :: Identity a -> Int #

elem :: Eq a => a -> Identity a -> Bool #

maximum :: Ord a => Identity a -> a #

minimum :: Ord a => Identity a -> a #

sum :: Num a => Identity a -> a #

product :: Num a => Identity a -> a #

Foldable First

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => First m -> m #

foldMap :: Monoid m => (a -> m) -> First a -> m #

foldMap' :: Monoid m => (a -> m) -> First a -> m #

foldr :: (a -> b -> b) -> b -> First a -> b #

foldr' :: (a -> b -> b) -> b -> First a -> b #

foldl :: (b -> a -> b) -> b -> First a -> b #

foldl' :: (b -> a -> b) -> b -> First a -> b #

foldr1 :: (a -> a -> a) -> First a -> a #

foldl1 :: (a -> a -> a) -> First a -> a #

toList :: First a -> [a] #

null :: First a -> Bool #

length :: First a -> Int #

elem :: Eq a => a -> First a -> Bool #

maximum :: Ord a => First a -> a #

minimum :: Ord a => First a -> a #

sum :: Num a => First a -> a #

product :: Num a => First a -> a #

Foldable Last

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Last m -> m #

foldMap :: Monoid m => (a -> m) -> Last a -> m #

foldMap' :: Monoid m => (a -> m) -> Last a -> m #

foldr :: (a -> b -> b) -> b -> Last a -> b #

foldr' :: (a -> b -> b) -> b -> Last a -> b #

foldl :: (b -> a -> b) -> b -> Last a -> b #

foldl' :: (b -> a -> b) -> b -> Last a -> b #

foldr1 :: (a -> a -> a) -> Last a -> a #

foldl1 :: (a -> a -> a) -> Last a -> a #

toList :: Last a -> [a] #

null :: Last a -> Bool #

length :: Last a -> Int #

elem :: Eq a => a -> Last a -> Bool #

maximum :: Ord a => Last a -> a #

minimum :: Ord a => Last a -> a #

sum :: Num a => Last a -> a #

product :: Num a => Last a -> a #

Foldable Down

Since: base-4.12.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Down m -> m #

foldMap :: Monoid m => (a -> m) -> Down a -> m #

foldMap' :: Monoid m => (a -> m) -> Down a -> m #

foldr :: (a -> b -> b) -> b -> Down a -> b #

foldr' :: (a -> b -> b) -> b -> Down a -> b #

foldl :: (b -> a -> b) -> b -> Down a -> b #

foldl' :: (b -> a -> b) -> b -> Down a -> b #

foldr1 :: (a -> a -> a) -> Down a -> a #

foldl1 :: (a -> a -> a) -> Down a -> a #

toList :: Down a -> [a] #

null :: Down a -> Bool #

length :: Down a -> Int #

elem :: Eq a => a -> Down a -> Bool #

maximum :: Ord a => Down a -> a #

minimum :: Ord a => Down a -> a #

sum :: Num a => Down a -> a #

product :: Num a => Down a -> a #

Foldable First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => First m -> m #

foldMap :: Monoid m => (a -> m) -> First a -> m #

foldMap' :: Monoid m => (a -> m) -> First a -> m #

foldr :: (a -> b -> b) -> b -> First a -> b #

foldr' :: (a -> b -> b) -> b -> First a -> b #

foldl :: (b -> a -> b) -> b -> First a -> b #

foldl' :: (b -> a -> b) -> b -> First a -> b #

foldr1 :: (a -> a -> a) -> First a -> a #

foldl1 :: (a -> a -> a) -> First a -> a #

toList :: First a -> [a] #

null :: First a -> Bool #

length :: First a -> Int #

elem :: Eq a => a -> First a -> Bool #

maximum :: Ord a => First a -> a #

minimum :: Ord a => First a -> a #

sum :: Num a => First a -> a #

product :: Num a => First a -> a #

Foldable Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Last m -> m #

foldMap :: Monoid m => (a -> m) -> Last a -> m #

foldMap' :: Monoid m => (a -> m) -> Last a -> m #

foldr :: (a -> b -> b) -> b -> Last a -> b #

foldr' :: (a -> b -> b) -> b -> Last a -> b #

foldl :: (b -> a -> b) -> b -> Last a -> b #

foldl' :: (b -> a -> b) -> b -> Last a -> b #

foldr1 :: (a -> a -> a) -> Last a -> a #

foldl1 :: (a -> a -> a) -> Last a -> a #

toList :: Last a -> [a] #

null :: Last a -> Bool #

length :: Last a -> Int #

elem :: Eq a => a -> Last a -> Bool #

maximum :: Ord a => Last a -> a #

minimum :: Ord a => Last a -> a #

sum :: Num a => Last a -> a #

product :: Num a => Last a -> a #

Foldable Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Max m -> m #

foldMap :: Monoid m => (a -> m) -> Max a -> m #

foldMap' :: Monoid m => (a -> m) -> Max a -> m #

foldr :: (a -> b -> b) -> b -> Max a -> b #

foldr' :: (a -> b -> b) -> b -> Max a -> b #

foldl :: (b -> a -> b) -> b -> Max a -> b #

foldl' :: (b -> a -> b) -> b -> Max a -> b #

foldr1 :: (a -> a -> a) -> Max a -> a #

foldl1 :: (a -> a -> a) -> Max a -> a #

toList :: Max a -> [a] #

null :: Max a -> Bool #

length :: Max a -> Int #

elem :: Eq a => a -> Max a -> Bool #

maximum :: Ord a => Max a -> a #

minimum :: Ord a => Max a -> a #

sum :: Num a => Max a -> a #

product :: Num a => Max a -> a #

Foldable Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Min m -> m #

foldMap :: Monoid m => (a -> m) -> Min a -> m #

foldMap' :: Monoid m => (a -> m) -> Min a -> m #

foldr :: (a -> b -> b) -> b -> Min a -> b #

foldr' :: (a -> b -> b) -> b -> Min a -> b #

foldl :: (b -> a -> b) -> b -> Min a -> b #

foldl' :: (b -> a -> b) -> b -> Min a -> b #

foldr1 :: (a -> a -> a) -> Min a -> a #

foldl1 :: (a -> a -> a) -> Min a -> a #

toList :: Min a -> [a] #

null :: Min a -> Bool #

length :: Min a -> Int #

elem :: Eq a => a -> Min a -> Bool #

maximum :: Ord a => Min a -> a #

minimum :: Ord a => Min a -> a #

sum :: Num a => Min a -> a #

product :: Num a => Min a -> a #

Foldable Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Dual m -> m #

foldMap :: Monoid m => (a -> m) -> Dual a -> m #

foldMap' :: Monoid m => (a -> m) -> Dual a -> m #

foldr :: (a -> b -> b) -> b -> Dual a -> b #

foldr' :: (a -> b -> b) -> b -> Dual a -> b #

foldl :: (b -> a -> b) -> b -> Dual a -> b #

foldl' :: (b -> a -> b) -> b -> Dual a -> b #

foldr1 :: (a -> a -> a) -> Dual a -> a #

foldl1 :: (a -> a -> a) -> Dual a -> a #

toList :: Dual a -> [a] #

null :: Dual a -> Bool #

length :: Dual a -> Int #

elem :: Eq a => a -> Dual a -> Bool #

maximum :: Ord a => Dual a -> a #

minimum :: Ord a => Dual a -> a #

sum :: Num a => Dual a -> a #

product :: Num a => Dual a -> a #

Foldable Product

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Product m -> m #

foldMap :: Monoid m => (a -> m) -> Product a -> m #

foldMap' :: Monoid m => (a -> m) -> Product a -> m #

foldr :: (a -> b -> b) -> b -> Product a -> b #

foldr' :: (a -> b -> b) -> b -> Product a -> b #

foldl :: (b -> a -> b) -> b -> Product a -> b #

foldl' :: (b -> a -> b) -> b -> Product a -> b #

foldr1 :: (a -> a -> a) -> Product a -> a #

foldl1 :: (a -> a -> a) -> Product a -> a #

toList :: Product a -> [a] #

null :: Product a -> Bool #

length :: Product a -> Int #

elem :: Eq a => a -> Product a -> Bool #

maximum :: Ord a => Product a -> a #

minimum :: Ord a => Product a -> a #

sum :: Num a => Product a -> a #

product :: Num a => Product a -> a #

Foldable Sum

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Sum m -> m #

foldMap :: Monoid m => (a -> m) -> Sum a -> m #

foldMap' :: Monoid m => (a -> m) -> Sum a -> m #

foldr :: (a -> b -> b) -> b -> Sum a -> b #

foldr' :: (a -> b -> b) -> b -> Sum a -> b #

foldl :: (b -> a -> b) -> b -> Sum a -> b #

foldl' :: (b -> a -> b) -> b -> Sum a -> b #

foldr1 :: (a -> a -> a) -> Sum a -> a #

foldl1 :: (a -> a -> a) -> Sum a -> a #

toList :: Sum a -> [a] #

null :: Sum a -> Bool #

length :: Sum a -> Int #

elem :: Eq a => a -> Sum a -> Bool #

maximum :: Ord a => Sum a -> a #

minimum :: Ord a => Sum a -> a #

sum :: Num a => Sum a -> a #

product :: Num a => Sum a -> a #

Foldable NonEmpty

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => NonEmpty m -> m #

foldMap :: Monoid m => (a -> m) -> NonEmpty a -> m #

foldMap' :: Monoid m => (a -> m) -> NonEmpty a -> m #

foldr :: (a -> b -> b) -> b -> NonEmpty a -> b #

foldr' :: (a -> b -> b) -> b -> NonEmpty a -> b #

foldl :: (b -> a -> b) -> b -> NonEmpty a -> b #

foldl' :: (b -> a -> b) -> b -> NonEmpty a -> b #

foldr1 :: (a -> a -> a) -> NonEmpty a -> a #

foldl1 :: (a -> a -> a) -> NonEmpty a -> a #

toList :: NonEmpty a -> [a] #

null :: NonEmpty a -> Bool #

length :: NonEmpty a -> Int #

elem :: Eq a => a -> NonEmpty a -> Bool #

maximum :: Ord a => NonEmpty a -> a #

minimum :: Ord a => NonEmpty a -> a #

sum :: Num a => NonEmpty a -> a #

product :: Num a => NonEmpty a -> a #

Foldable Par1

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Par1 m -> m #

foldMap :: Monoid m => (a -> m) -> Par1 a -> m #

foldMap' :: Monoid m => (a -> m) -> Par1 a -> m #

foldr :: (a -> b -> b) -> b -> Par1 a -> b #

foldr' :: (a -> b -> b) -> b -> Par1 a -> b #

foldl :: (b -> a -> b) -> b -> Par1 a -> b #

foldl' :: (b -> a -> b) -> b -> Par1 a -> b #

foldr1 :: (a -> a -> a) -> Par1 a -> a #

foldl1 :: (a -> a -> a) -> Par1 a -> a #

toList :: Par1 a -> [a] #

null :: Par1 a -> Bool #

length :: Par1 a -> Int #

elem :: Eq a => a -> Par1 a -> Bool #

maximum :: Ord a => Par1 a -> a #

minimum :: Ord a => Par1 a -> a #

sum :: Num a => Par1 a -> a #

product :: Num a => Par1 a -> a #

Foldable Maybe

Since: base-2.1

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Maybe m -> m #

foldMap :: Monoid m => (a -> m) -> Maybe a -> m #

foldMap' :: Monoid m => (a -> m) -> Maybe a -> m #

foldr :: (a -> b -> b) -> b -> Maybe a -> b #

foldr' :: (a -> b -> b) -> b -> Maybe a -> b #

foldl :: (b -> a -> b) -> b -> Maybe a -> b #

foldl' :: (b -> a -> b) -> b -> Maybe a -> b #

foldr1 :: (a -> a -> a) -> Maybe a -> a #

foldl1 :: (a -> a -> a) -> Maybe a -> a #

toList :: Maybe a -> [a] #

null :: Maybe a -> Bool #

length :: Maybe a -> Int #

elem :: Eq a => a -> Maybe a -> Bool #

maximum :: Ord a => Maybe a -> a #

minimum :: Ord a => Maybe a -> a #

sum :: Num a => Maybe a -> a #

product :: Num a => Maybe a -> a #

Foldable Solo

Since: base-4.15

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Solo m -> m #

foldMap :: Monoid m => (a -> m) -> Solo a -> m #

foldMap' :: Monoid m => (a -> m) -> Solo a -> m #

foldr :: (a -> b -> b) -> b -> Solo a -> b #

foldr' :: (a -> b -> b) -> b -> Solo a -> b #

foldl :: (b -> a -> b) -> b -> Solo a -> b #

foldl' :: (b -> a -> b) -> b -> Solo a -> b #

foldr1 :: (a -> a -> a) -> Solo a -> a #

foldl1 :: (a -> a -> a) -> Solo a -> a #

toList :: Solo a -> [a] #

null :: Solo a -> Bool #

length :: Solo a -> Int #

elem :: Eq a => a -> Solo a -> Bool #

maximum :: Ord a => Solo a -> a #

minimum :: Ord a => Solo a -> a #

sum :: Num a => Solo a -> a #

product :: Num a => Solo a -> a #

Foldable List

Since: base-2.1

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => [m] -> m #

foldMap :: Monoid m => (a -> m) -> [a] -> m #

foldMap' :: Monoid m => (a -> m) -> [a] -> m #

foldr :: (a -> b -> b) -> b -> [a] -> b #

foldr' :: (a -> b -> b) -> b -> [a] -> b #

foldl :: (b -> a -> b) -> b -> [a] -> b #

foldl' :: (b -> a -> b) -> b -> [a] -> b #

foldr1 :: (a -> a -> a) -> [a] -> a #

foldl1 :: (a -> a -> a) -> [a] -> a #

toList :: [a] -> [a] #

null :: [a] -> Bool #

length :: [a] -> Int #

elem :: Eq a => a -> [a] -> Bool #

maximum :: Ord a => [a] -> a #

minimum :: Ord a => [a] -> a #

sum :: Num a => [a] -> a #

product :: Num a => [a] -> a #

Foldable (Either a)

Since: base-4.7.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Either a m -> m #

foldMap :: Monoid m => (a0 -> m) -> Either a a0 -> m #

foldMap' :: Monoid m => (a0 -> m) -> Either a a0 -> m #

foldr :: (a0 -> b -> b) -> b -> Either a a0 -> b #

foldr' :: (a0 -> b -> b) -> b -> Either a a0 -> b #

foldl :: (b -> a0 -> b) -> b -> Either a a0 -> b #

foldl' :: (b -> a0 -> b) -> b -> Either a a0 -> b #

foldr1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 #

toList :: Either a a0 -> [a0] #

null :: Either a a0 -> Bool #

length :: Either a a0 -> Int #

elem :: Eq a0 => a0 -> Either a a0 -> Bool #

maximum :: Ord a0 => Either a a0 -> a0 #

minimum :: Ord a0 => Either a a0 -> a0 #

sum :: Num a0 => Either a a0 -> a0 #

product :: Num a0 => Either a a0 -> a0 #

Foldable (Proxy :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Proxy m -> m #

foldMap :: Monoid m => (a -> m) -> Proxy a -> m #

foldMap' :: Monoid m => (a -> m) -> Proxy a -> m #

foldr :: (a -> b -> b) -> b -> Proxy a -> b #

foldr' :: (a -> b -> b) -> b -> Proxy a -> b #

foldl :: (b -> a -> b) -> b -> Proxy a -> b #

foldl' :: (b -> a -> b) -> b -> Proxy a -> b #

foldr1 :: (a -> a -> a) -> Proxy a -> a #

foldl1 :: (a -> a -> a) -> Proxy a -> a #

toList :: Proxy a -> [a] #

null :: Proxy a -> Bool #

length :: Proxy a -> Int #

elem :: Eq a => a -> Proxy a -> Bool #

maximum :: Ord a => Proxy a -> a #

minimum :: Ord a => Proxy a -> a #

sum :: Num a => Proxy a -> a #

product :: Num a => Proxy a -> a #

Foldable (Arg a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Arg a m -> m #

foldMap :: Monoid m => (a0 -> m) -> Arg a a0 -> m #

foldMap' :: Monoid m => (a0 -> m) -> Arg a a0 -> m #

foldr :: (a0 -> b -> b) -> b -> Arg a a0 -> b #

foldr' :: (a0 -> b -> b) -> b -> Arg a a0 -> b #

foldl :: (b -> a0 -> b) -> b -> Arg a a0 -> b #

foldl' :: (b -> a0 -> b) -> b -> Arg a a0 -> b #

foldr1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 #

toList :: Arg a a0 -> [a0] #

null :: Arg a a0 -> Bool #

length :: Arg a a0 -> Int #

elem :: Eq a0 => a0 -> Arg a a0 -> Bool #

maximum :: Ord a0 => Arg a a0 -> a0 #

minimum :: Ord a0 => Arg a a0 -> a0 #

sum :: Num a0 => Arg a a0 -> a0 #

product :: Num a0 => Arg a a0 -> a0 #

Foldable (Array i)

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Array i m -> m #

foldMap :: Monoid m => (a -> m) -> Array i a -> m #

foldMap' :: Monoid m => (a -> m) -> Array i a -> m #

foldr :: (a -> b -> b) -> b -> Array i a -> b #

foldr' :: (a -> b -> b) -> b -> Array i a -> b #

foldl :: (b -> a -> b) -> b -> Array i a -> b #

foldl' :: (b -> a -> b) -> b -> Array i a -> b #

foldr1 :: (a -> a -> a) -> Array i a -> a #

foldl1 :: (a -> a -> a) -> Array i a -> a #

toList :: Array i a -> [a] #

null :: Array i a -> Bool #

length :: Array i a -> Int #

elem :: Eq a => a -> Array i a -> Bool #

maximum :: Ord a => Array i a -> a #

minimum :: Ord a => Array i a -> a #

sum :: Num a => Array i a -> a #

product :: Num a => Array i a -> a #

Foldable (U1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => U1 m -> m #

foldMap :: Monoid m => (a -> m) -> U1 a -> m #

foldMap' :: Monoid m => (a -> m) -> U1 a -> m #

foldr :: (a -> b -> b) -> b -> U1 a -> b #

foldr' :: (a -> b -> b) -> b -> U1 a -> b #

foldl :: (b -> a -> b) -> b -> U1 a -> b #

foldl' :: (b -> a -> b) -> b -> U1 a -> b #

foldr1 :: (a -> a -> a) -> U1 a -> a #

foldl1 :: (a -> a -> a) -> U1 a -> a #

toList :: U1 a -> [a] #

null :: U1 a -> Bool #

length :: U1 a -> Int #

elem :: Eq a => a -> U1 a -> Bool #

maximum :: Ord a => U1 a -> a #

minimum :: Ord a => U1 a -> a #

sum :: Num a => U1 a -> a #

product :: Num a => U1 a -> a #

Foldable (UAddr :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UAddr m -> m #

foldMap :: Monoid m => (a -> m) -> UAddr a -> m #

foldMap' :: Monoid m => (a -> m) -> UAddr a -> m #

foldr :: (a -> b -> b) -> b -> UAddr a -> b #

foldr' :: (a -> b -> b) -> b -> UAddr a -> b #

foldl :: (b -> a -> b) -> b -> UAddr a -> b #

foldl' :: (b -> a -> b) -> b -> UAddr a -> b #

foldr1 :: (a -> a -> a) -> UAddr a -> a #

foldl1 :: (a -> a -> a) -> UAddr a -> a #

toList :: UAddr a -> [a] #

null :: UAddr a -> Bool #

length :: UAddr a -> Int #

elem :: Eq a => a -> UAddr a -> Bool #

maximum :: Ord a => UAddr a -> a #

minimum :: Ord a => UAddr a -> a #

sum :: Num a => UAddr a -> a #

product :: Num a => UAddr a -> a #

Foldable (UChar :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UChar m -> m #

foldMap :: Monoid m => (a -> m) -> UChar a -> m #

foldMap' :: Monoid m => (a -> m) -> UChar a -> m #

foldr :: (a -> b -> b) -> b -> UChar a -> b #

foldr' :: (a -> b -> b) -> b -> UChar a -> b #

foldl :: (b -> a -> b) -> b -> UChar a -> b #

foldl' :: (b -> a -> b) -> b -> UChar a -> b #

foldr1 :: (a -> a -> a) -> UChar a -> a #

foldl1 :: (a -> a -> a) -> UChar a -> a #

toList :: UChar a -> [a] #

null :: UChar a -> Bool #

length :: UChar a -> Int #

elem :: Eq a => a -> UChar a -> Bool #

maximum :: Ord a => UChar a -> a #

minimum :: Ord a => UChar a -> a #

sum :: Num a => UChar a -> a #

product :: Num a => UChar a -> a #

Foldable (UDouble :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UDouble m -> m #

foldMap :: Monoid m => (a -> m) -> UDouble a -> m #

foldMap' :: Monoid m => (a -> m) -> UDouble a -> m #

foldr :: (a -> b -> b) -> b -> UDouble a -> b #

foldr' :: (a -> b -> b) -> b -> UDouble a -> b #

foldl :: (b -> a -> b) -> b -> UDouble a -> b #

foldl' :: (b -> a -> b) -> b -> UDouble a -> b #

foldr1 :: (a -> a -> a) -> UDouble a -> a #

foldl1 :: (a -> a -> a) -> UDouble a -> a #

toList :: UDouble a -> [a] #

null :: UDouble a -> Bool #

length :: UDouble a -> Int #

elem :: Eq a => a -> UDouble a -> Bool #

maximum :: Ord a => UDouble a -> a #

minimum :: Ord a => UDouble a -> a #

sum :: Num a => UDouble a -> a #

product :: Num a => UDouble a -> a #

Foldable (UFloat :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UFloat m -> m #

foldMap :: Monoid m => (a -> m) -> UFloat a -> m #

foldMap' :: Monoid m => (a -> m) -> UFloat a -> m #

foldr :: (a -> b -> b) -> b -> UFloat a -> b #

foldr' :: (a -> b -> b) -> b -> UFloat a -> b #

foldl :: (b -> a -> b) -> b -> UFloat a -> b #

foldl' :: (b -> a -> b) -> b -> UFloat a -> b #

foldr1 :: (a -> a -> a) -> UFloat a -> a #

foldl1 :: (a -> a -> a) -> UFloat a -> a #

toList :: UFloat a -> [a] #

null :: UFloat a -> Bool #

length :: UFloat a -> Int #

elem :: Eq a => a -> UFloat a -> Bool #

maximum :: Ord a => UFloat a -> a #

minimum :: Ord a => UFloat a -> a #

sum :: Num a => UFloat a -> a #

product :: Num a => UFloat a -> a #

Foldable (UInt :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UInt m -> m #

foldMap :: Monoid m => (a -> m) -> UInt a -> m #

foldMap' :: Monoid m => (a -> m) -> UInt a -> m #

foldr :: (a -> b -> b) -> b -> UInt a -> b #

foldr' :: (a -> b -> b) -> b -> UInt a -> b #

foldl :: (b -> a -> b) -> b -> UInt a -> b #

foldl' :: (b -> a -> b) -> b -> UInt a -> b #

foldr1 :: (a -> a -> a) -> UInt a -> a #

foldl1 :: (a -> a -> a) -> UInt a -> a #

toList :: UInt a -> [a] #

null :: UInt a -> Bool #

length :: UInt a -> Int #

elem :: Eq a => a -> UInt a -> Bool #

maximum :: Ord a => UInt a -> a #

minimum :: Ord a => UInt a -> a #

sum :: Num a => UInt a -> a #

product :: Num a => UInt a -> a #

Foldable (UWord :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UWord m -> m #

foldMap :: Monoid m => (a -> m) -> UWord a -> m #

foldMap' :: Monoid m => (a -> m) -> UWord a -> m #

foldr :: (a -> b -> b) -> b -> UWord a -> b #

foldr' :: (a -> b -> b) -> b -> UWord a -> b #

foldl :: (b -> a -> b) -> b -> UWord a -> b #

foldl' :: (b -> a -> b) -> b -> UWord a -> b #

foldr1 :: (a -> a -> a) -> UWord a -> a #

foldl1 :: (a -> a -> a) -> UWord a -> a #

toList :: UWord a -> [a] #

null :: UWord a -> Bool #

length :: UWord a -> Int #

elem :: Eq a => a -> UWord a -> Bool #

maximum :: Ord a => UWord a -> a #

minimum :: Ord a => UWord a -> a #

sum :: Num a => UWord a -> a #

product :: Num a => UWord a -> a #

Foldable (V1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => V1 m -> m #

foldMap :: Monoid m => (a -> m) -> V1 a -> m #

foldMap' :: Monoid m => (a -> m) -> V1 a -> m #

foldr :: (a -> b -> b) -> b -> V1 a -> b #

foldr' :: (a -> b -> b) -> b -> V1 a -> b #

foldl :: (b -> a -> b) -> b -> V1 a -> b #

foldl' :: (b -> a -> b) -> b -> V1 a -> b #

foldr1 :: (a -> a -> a) -> V1 a -> a #

foldl1 :: (a -> a -> a) -> V1 a -> a #

toList :: V1 a -> [a] #

null :: V1 a -> Bool #

length :: V1 a -> Int #

elem :: Eq a => a -> V1 a -> Bool #

maximum :: Ord a => V1 a -> a #

minimum :: Ord a => V1 a -> a #

sum :: Num a => V1 a -> a #

product :: Num a => V1 a -> a #

Foldable ((,) a)

Since: base-4.7.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (a, m) -> m #

foldMap :: Monoid m => (a0 -> m) -> (a, a0) -> m #

foldMap' :: Monoid m => (a0 -> m) -> (a, a0) -> m #

foldr :: (a0 -> b -> b) -> b -> (a, a0) -> b #

foldr' :: (a0 -> b -> b) -> b -> (a, a0) -> b #

foldl :: (b -> a0 -> b) -> b -> (a, a0) -> b #

foldl' :: (b -> a0 -> b) -> b -> (a, a0) -> b #

foldr1 :: (a0 -> a0 -> a0) -> (a, a0) -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> (a, a0) -> a0 #

toList :: (a, a0) -> [a0] #

null :: (a, a0) -> Bool #

length :: (a, a0) -> Int #

elem :: Eq a0 => a0 -> (a, a0) -> Bool #

maximum :: Ord a0 => (a, a0) -> a0 #

minimum :: Ord a0 => (a, a0) -> a0 #

sum :: Num a0 => (a, a0) -> a0 #

product :: Num a0 => (a, a0) -> a0 #

Foldable (Const m :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in Data.Functor.Const

Methods

fold :: Monoid m0 => Const m m0 -> m0 #

foldMap :: Monoid m0 => (a -> m0) -> Const m a -> m0 #

foldMap' :: Monoid m0 => (a -> m0) -> Const m a -> m0 #

foldr :: (a -> b -> b) -> b -> Const m a -> b #

foldr' :: (a -> b -> b) -> b -> Const m a -> b #

foldl :: (b -> a -> b) -> b -> Const m a -> b #

foldl' :: (b -> a -> b) -> b -> Const m a -> b #

foldr1 :: (a -> a -> a) -> Const m a -> a #

foldl1 :: (a -> a -> a) -> Const m a -> a #

toList :: Const m a -> [a] #

null :: Const m a -> Bool #

length :: Const m a -> Int #

elem :: Eq a => a -> Const m a -> Bool #

maximum :: Ord a => Const m a -> a #

minimum :: Ord a => Const m a -> a #

sum :: Num a => Const m a -> a #

product :: Num a => Const m a -> a #

Foldable f => Foldable (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Ap f m -> m #

foldMap :: Monoid m => (a -> m) -> Ap f a -> m #

foldMap' :: Monoid m => (a -> m) -> Ap f a -> m #

foldr :: (a -> b -> b) -> b -> Ap f a -> b #

foldr' :: (a -> b -> b) -> b -> Ap f a -> b #

foldl :: (b -> a -> b) -> b -> Ap f a -> b #

foldl' :: (b -> a -> b) -> b -> Ap f a -> b #

foldr1 :: (a -> a -> a) -> Ap f a -> a #

foldl1 :: (a -> a -> a) -> Ap f a -> a #

toList :: Ap f a -> [a] #

null :: Ap f a -> Bool #

length :: Ap f a -> Int #

elem :: Eq a => a -> Ap f a -> Bool #

maximum :: Ord a => Ap f a -> a #

minimum :: Ord a => Ap f a -> a #

sum :: Num a => Ap f a -> a #

product :: Num a => Ap f a -> a #

Foldable f => Foldable (Alt f)

Since: base-4.12.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Alt f m -> m #

foldMap :: Monoid m => (a -> m) -> Alt f a -> m #

foldMap' :: Monoid m => (a -> m) -> Alt f a -> m #

foldr :: (a -> b -> b) -> b -> Alt f a -> b #

foldr' :: (a -> b -> b) -> b -> Alt f a -> b #

foldl :: (b -> a -> b) -> b -> Alt f a -> b #

foldl' :: (b -> a -> b) -> b -> Alt f a -> b #

foldr1 :: (a -> a -> a) -> Alt f a -> a #

foldl1 :: (a -> a -> a) -> Alt f a -> a #

toList :: Alt f a -> [a] #

null :: Alt f a -> Bool #

length :: Alt f a -> Int #

elem :: Eq a => a -> Alt f a -> Bool #

maximum :: Ord a => Alt f a -> a #

minimum :: Ord a => Alt f a -> a #

sum :: Num a => Alt f a -> a #

product :: Num a => Alt f a -> a #

Foldable f => Foldable (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Rec1 f m -> m #

foldMap :: Monoid m => (a -> m) -> Rec1 f a -> m #

foldMap' :: Monoid m => (a -> m) -> Rec1 f a -> m #

foldr :: (a -> b -> b) -> b -> Rec1 f a -> b #

foldr' :: (a -> b -> b) -> b -> Rec1 f a -> b #

foldl :: (b -> a -> b) -> b -> Rec1 f a -> b #

foldl' :: (b -> a -> b) -> b -> Rec1 f a -> b #

foldr1 :: (a -> a -> a) -> Rec1 f a -> a #

foldl1 :: (a -> a -> a) -> Rec1 f a -> a #

toList :: Rec1 f a -> [a] #

null :: Rec1 f a -> Bool #

length :: Rec1 f a -> Int #

elem :: Eq a => a -> Rec1 f a -> Bool #

maximum :: Ord a => Rec1 f a -> a #

minimum :: Ord a => Rec1 f a -> a #

sum :: Num a => Rec1 f a -> a #

product :: Num a => Rec1 f a -> a #

(Foldable f, Foldable g) => Foldable (f :*: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (f :*: g) m -> m #

foldMap :: Monoid m => (a -> m) -> (f :*: g) a -> m #

foldMap' :: Monoid m => (a -> m) -> (f :*: g) a -> m #

foldr :: (a -> b -> b) -> b -> (f :*: g) a -> b #

foldr' :: (a -> b -> b) -> b -> (f :*: g) a -> b #

foldl :: (b -> a -> b) -> b -> (f :*: g) a -> b #

foldl' :: (b -> a -> b) -> b -> (f :*: g) a -> b #

foldr1 :: (a -> a -> a) -> (f :*: g) a -> a #

foldl1 :: (a -> a -> a) -> (f :*: g) a -> a #

toList :: (f :*: g) a -> [a] #

null :: (f :*: g) a -> Bool #

length :: (f :*: g) a -> Int #

elem :: Eq a => a -> (f :*: g) a -> Bool #

maximum :: Ord a => (f :*: g) a -> a #

minimum :: Ord a => (f :*: g) a -> a #

sum :: Num a => (f :*: g) a -> a #

product :: Num a => (f :*: g) a -> a #

(Foldable f, Foldable g) => Foldable (f :+: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (f :+: g) m -> m #

foldMap :: Monoid m => (a -> m) -> (f :+: g) a -> m #

foldMap' :: Monoid m => (a -> m) -> (f :+: g) a -> m #

foldr :: (a -> b -> b) -> b -> (f :+: g) a -> b #

foldr' :: (a -> b -> b) -> b -> (f :+: g) a -> b #

foldl :: (b -> a -> b) -> b -> (f :+: g) a -> b #

foldl' :: (b -> a -> b) -> b -> (f :+: g) a -> b #

foldr1 :: (a -> a -> a) -> (f :+: g) a -> a #

foldl1 :: (a -> a -> a) -> (f :+: g) a -> a #

toList :: (f :+: g) a -> [a] #

null :: (f :+: g) a -> Bool #

length :: (f :+: g) a -> Int #

elem :: Eq a => a -> (f :+: g) a -> Bool #

maximum :: Ord a => (f :+: g) a -> a #

minimum :: Ord a => (f :+: g) a -> a #

sum :: Num a => (f :+: g) a -> a #

product :: Num a => (f :+: g) a -> a #

Foldable (K1 i c :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => K1 i c m -> m #

foldMap :: Monoid m => (a -> m) -> K1 i c a -> m #

foldMap' :: Monoid m => (a -> m) -> K1 i c a -> m #

foldr :: (a -> b -> b) -> b -> K1 i c a -> b #

foldr' :: (a -> b -> b) -> b -> K1 i c a -> b #

foldl :: (b -> a -> b) -> b -> K1 i c a -> b #

foldl' :: (b -> a -> b) -> b -> K1 i c a -> b #

foldr1 :: (a -> a -> a) -> K1 i c a -> a #

foldl1 :: (a -> a -> a) -> K1 i c a -> a #

toList :: K1 i c a -> [a] #

null :: K1 i c a -> Bool #

length :: K1 i c a -> Int #

elem :: Eq a => a -> K1 i c a -> Bool #

maximum :: Ord a => K1 i c a -> a #

minimum :: Ord a => K1 i c a -> a #

sum :: Num a => K1 i c a -> a #

product :: Num a => K1 i c a -> a #

(Foldable f, Foldable g) => Foldable (f :.: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (f :.: g) m -> m #

foldMap :: Monoid m => (a -> m) -> (f :.: g) a -> m #

foldMap' :: Monoid m => (a -> m) -> (f :.: g) a -> m #

foldr :: (a -> b -> b) -> b -> (f :.: g) a -> b #

foldr' :: (a -> b -> b) -> b -> (f :.: g) a -> b #

foldl :: (b -> a -> b) -> b -> (f :.: g) a -> b #

foldl' :: (b -> a -> b) -> b -> (f :.: g) a -> b #

foldr1 :: (a -> a -> a) -> (f :.: g) a -> a #

foldl1 :: (a -> a -> a) -> (f :.: g) a -> a #

toList :: (f :.: g) a -> [a] #

null :: (f :.: g) a -> Bool #

length :: (f :.: g) a -> Int #

elem :: Eq a => a -> (f :.: g) a -> Bool #

maximum :: Ord a => (f :.: g) a -> a #

minimum :: Ord a => (f :.: g) a -> a #

sum :: Num a => (f :.: g) a -> a #

product :: Num a => (f :.: g) a -> a #

Foldable f => Foldable (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => M1 i c f m -> m #

foldMap :: Monoid m => (a -> m) -> M1 i c f a -> m #

foldMap' :: Monoid m => (a -> m) -> M1 i c f a -> m #

foldr :: (a -> b -> b) -> b -> M1 i c f a -> b #

foldr' :: (a -> b -> b) -> b -> M1 i c f a -> b #

foldl :: (b -> a -> b) -> b -> M1 i c f a -> b #

foldl' :: (b -> a -> b) -> b -> M1 i c f a -> b #

foldr1 :: (a -> a -> a) -> M1 i c f a -> a #

foldl1 :: (a -> a -> a) -> M1 i c f a -> a #

toList :: M1 i c f a -> [a] #

null :: M1 i c f a -> Bool #

length :: M1 i c f a -> Int #

elem :: Eq a => a -> M1 i c f a -> Bool #

maximum :: Ord a => M1 i c f a -> a #

minimum :: Ord a => M1 i c f a -> a #

sum :: Num a => M1 i c f a -> a #

product :: Num a => M1 i c f a -> a #

maximumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a #

The largest element of a non-empty structure with respect to the given comparison function.

Examples

Expand

Basic usage:

>>> maximumBy (compare `on` length) ["Hello", "World", "!", "Longest", "bar"]
"Longest"

WARNING: This function is partial for possibly-empty structures like lists.

minimumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a #

The least element of a non-empty structure with respect to the given comparison function.

Examples

Expand

Basic usage:

>>> minimumBy (compare `on` length) ["Hello", "World", "!", "Longest", "bar"]
"!"

WARNING: This function is partial for possibly-empty structures like lists.

concat :: Foldable t => t [a] -> [a] #

The concatenation of all the elements of a container of lists.

Examples

Expand

Basic usage:

>>> concat (Just [1, 2, 3])
[1,2,3]
>>> concat (Left 42)
[]
>>> concat [[1, 2, 3], [4, 5], [6], []]
[1,2,3,4,5,6]

and :: Foldable t => t Bool -> Bool #

and returns the conjunction of a container of Bools. For the result to be True, the container must be finite; False, however, results from a False value finitely far from the left end.

Examples

Expand

Basic usage:

>>> and []
True
>>> and [True]
True
>>> and [False]
False
>>> and [True, True, False]
False
>>> and (False : repeat True) -- Infinite list [False,True,True,True,...
False
>>> and (repeat True)
* Hangs forever *

or :: Foldable t => t Bool -> Bool #

or returns the disjunction of a container of Bools. For the result to be False, the container must be finite; True, however, results from a True value finitely far from the left end.

Examples

Expand

Basic usage:

>>> or []
False
>>> or [True]
True
>>> or [False]
False
>>> or [True, True, False]
True
>>> or (True : repeat False) -- Infinite list [True,False,False,False,...
True
>>> or (repeat False)
* Hangs forever *

any :: Foldable t => (a -> Bool) -> t a -> Bool #

Determines whether any element of the structure satisfies the predicate.

Examples

Expand

Basic usage:

>>> any (> 3) []
False
>>> any (> 3) [1,2]
False
>>> any (> 3) [1,2,3,4,5]
True
>>> any (> 3) [1..]
True
>>> any (> 3) [0, -1..]
* Hangs forever *

all :: Foldable t => (a -> Bool) -> t a -> Bool #

Determines whether all elements of the structure satisfy the predicate.

Examples

Expand

Basic usage:

>>> all (> 3) []
True
>>> all (> 3) [1,2]
False
>>> all (> 3) [1,2,3,4,5]
False
>>> all (> 3) [1..]
False
>>> all (> 3) [4..]
* Hangs forever *

notElem :: (Foldable t, Eq a) => a -> t a -> Bool infix 4 #

notElem is the negation of elem.

Examples

Expand

Basic usage:

>>> 3 `notElem` []
True
>>> 3 `notElem` [1,2]
True
>>> 3 `notElem` [1,2,3,4,5]
False

For infinite structures, notElem terminates if the value exists at a finite distance from the left side of the structure:

>>> 3 `notElem` [1..]
False
>>> 3 `notElem` ([4..] ++ [3])
* Hangs forever *

concatMap :: Foldable t => (a -> [b]) -> t a -> [b] #

Map a function over all the elements of a container and concatenate the resulting lists.

Examples

Expand

Basic usage:

>>> concatMap (take 3) [[1..], [10..], [100..], [1000..]]
[1,2,3,10,11,12,100,101,102,1000,1001,1002]
>>> concatMap (take 3) (Just [1..])
[1,2,3]

foldrM :: (Foldable t, Monad m) => (a -> b -> m b) -> b -> t a -> m b #

Right-to-left monadic fold over the elements of a structure.

Given a structure t with elements (a, b, c, ..., x, y), the result of a fold with an operator function f is equivalent to:

foldrM f z t = do
    yy <- f y z
    xx <- f x yy
    ...
    bb <- f b cc
    aa <- f a bb
    return aa -- Just @return z@ when the structure is empty

For a Monad m, given two functions f1 :: a -> m b and f2 :: b -> m c, their Kleisli composition (f1 >=> f2) :: a -> m c is defined by:

(f1 >=> f2) a = f1 a >>= f2

Another way of thinking about foldrM is that it amounts to an application to z of a Kleisli composition:

foldrM f z t = f y >=> f x >=> ... >=> f b >=> f a $ z

The monadic effects of foldrM are sequenced from right to left, and e.g. folds of infinite lists will diverge.

If at some step the bind operator (>>=) short-circuits (as with, e.g., mzero in a MonadPlus), the evaluated effects will be from a tail of the element sequence. If you want to evaluate the monadic effects in left-to-right order, or perhaps be able to short-circuit after an initial sequence of elements, you'll need to use foldlM instead.

If the monadic effects don't short-circuit, the outermost application of f is to the leftmost element a, so that, ignoring effects, the result looks like a right fold:

a `f` (b `f` (c `f` (... (x `f` (y `f` z))))).

Examples

Expand

Basic usage:

>>> let f i acc = do { print i ; return $ i : acc }
>>> foldrM f [] [0..3]
3
2
1
0
[0,1,2,3]

foldlM :: (Foldable t, Monad m) => (b -> a -> m b) -> b -> t a -> m b #

Left-to-right monadic fold over the elements of a structure.

Given a structure t with elements (a, b, ..., w, x, y), the result of a fold with an operator function f is equivalent to:

foldlM f z t = do
    aa <- f z a
    bb <- f aa b
    ...
    xx <- f ww x
    yy <- f xx y
    return yy -- Just @return z@ when the structure is empty

For a Monad m, given two functions f1 :: a -> m b and f2 :: b -> m c, their Kleisli composition (f1 >=> f2) :: a -> m c is defined by:

(f1 >=> f2) a = f1 a >>= f2

Another way of thinking about foldlM is that it amounts to an application to z of a Kleisli composition:

foldlM f z t =
    flip f a >=> flip f b >=> ... >=> flip f x >=> flip f y $ z

The monadic effects of foldlM are sequenced from left to right.

If at some step the bind operator (>>=) short-circuits (as with, e.g., mzero in a MonadPlus), the evaluated effects will be from an initial segment of the element sequence. If you want to evaluate the monadic effects in right-to-left order, or perhaps be able to short-circuit after processing a tail of the sequence of elements, you'll need to use foldrM instead.

If the monadic effects don't short-circuit, the outermost application of f is to the rightmost element y, so that, ignoring effects, the result looks like a left fold:

((((z `f` a) `f` b) ... `f` w) `f` x) `f` y

Examples

Expand

Basic usage:

>>> let f a e = do { print e ; return $ e : a }
>>> foldlM f [] [0..3]
0
1
2
3
[3,2,1,0]

traverse_ :: (Foldable t, Applicative f) => (a -> f b) -> t a -> f () #

Map each element of a structure to an Applicative action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see traverse.

traverse_ is just like mapM_, but generalised to Applicative actions.

Examples

Expand

Basic usage:

>>> traverse_ print ["Hello", "world", "!"]
"Hello"
"world"
"!"

for_ :: (Foldable t, Applicative f) => t a -> (a -> f b) -> f () #

for_ is traverse_ with its arguments flipped. For a version that doesn't ignore the results see for. This is forM_ generalised to Applicative actions.

for_ is just like forM_, but generalised to Applicative actions.

Examples

Expand

Basic usage:

>>> for_ [1..4] print
1
2
3
4

mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m () #

Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM.

mapM_ is just like traverse_, but specialised to monadic actions.

forM_ :: (Foldable t, Monad m) => t a -> (a -> m b) -> m () #

forM_ is mapM_ with its arguments flipped. For a version that doesn't ignore the results see forM.

forM_ is just like for_, but specialised to monadic actions.

sequenceA_ :: (Foldable t, Applicative f) => t (f a) -> f () #

Evaluate each action in the structure from left to right, and ignore the results. For a version that doesn't ignore the results see sequenceA.

sequenceA_ is just like sequence_, but generalised to Applicative actions.

Examples

Expand

Basic usage:

>>> sequenceA_ [print "Hello", print "world", print "!"]
"Hello"
"world"
"!"

sequence_ :: (Foldable t, Monad m) => t (m a) -> m () #

Evaluate each monadic action in the structure from left to right, and ignore the results. For a version that doesn't ignore the results see sequence.

sequence_ is just like sequenceA_, but specialised to monadic actions.

asum :: (Foldable t, Alternative f) => t (f a) -> f a #

The sum of a collection of actions using (<|>), generalizing concat.

asum is just like msum, but generalised to Alternative.

Examples

Expand

Basic usage:

>>> asum [Just "Hello", Nothing, Just "World"]
Just "Hello"

msum :: (Foldable t, MonadPlus m) => t (m a) -> m a #

The sum of a collection of actions using (<|>), generalizing concat.

msum is just like asum, but specialised to MonadPlus.

Examples

Expand

Basic usage, using the MonadPlus instance for Maybe:

>>> msum [Just "Hello", Nothing, Just "World"]
Just "Hello"

find :: Foldable t => (a -> Bool) -> t a -> Maybe a #

The find function takes a predicate and a structure and returns the leftmost element of the structure matching the predicate, or Nothing if there is no such element.

Examples

Expand

Basic usage:

>>> find (> 42) [0, 5..]
Just 45
>>> find (> 12) [1..7]
Nothing

The Prelude

data Int #

A fixed-precision integer type with at least the range [-2^29 .. 2^29-1]. The exact range for a given implementation can be determined by using minBound and maxBound from the Bounded class.

Instances

Instances details
Data Int

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Int -> c Int #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Int #

toConstr :: Int -> Constr #

dataTypeOf :: Int -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Int) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Int) #

gmapT :: (forall b. Data b => b -> b) -> Int -> Int #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Int -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Int -> r #

gmapQ :: (forall d. Data d => d -> u) -> Int -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Int -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Int -> m Int #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Int -> m Int #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Int -> m Int #

Bounded Int

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: Int #

maxBound :: Int #

Enum Int

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Int -> Int #

pred :: Int -> Int #

toEnum :: Int -> Int #

fromEnum :: Int -> Int #

enumFrom :: Int -> [Int] #

enumFromThen :: Int -> Int -> [Int] #

enumFromTo :: Int -> Int -> [Int] #

enumFromThenTo :: Int -> Int -> Int -> [Int] #

Num Int

Since: base-2.1

Instance details

Defined in GHC.Num

Methods

(+) :: Int -> Int -> Int #

(-) :: Int -> Int -> Int #

(*) :: Int -> Int -> Int #

negate :: Int -> Int #

abs :: Int -> Int #

signum :: Int -> Int #

fromInteger :: Integer -> Int #

Read Int

Since: base-2.1

Instance details

Defined in GHC.Read

Integral Int

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

quot :: Int -> Int -> Int #

rem :: Int -> Int -> Int #

div :: Int -> Int -> Int #

mod :: Int -> Int -> Int #

quotRem :: Int -> Int -> (Int, Int) #

divMod :: Int -> Int -> (Int, Int) #

toInteger :: Int -> Integer #

Real Int

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

toRational :: Int -> Rational #

Show Int

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Int -> ShowS #

show :: Int -> String #

showList :: [Int] -> ShowS #

Eq Int 
Instance details

Defined in GHC.Classes

Methods

(==) :: Int -> Int -> Bool #

(/=) :: Int -> Int -> Bool #

Ord Int 
Instance details

Defined in GHC.Classes

Methods

compare :: Int -> Int -> Ordering #

(<) :: Int -> Int -> Bool #

(<=) :: Int -> Int -> Bool #

(>) :: Int -> Int -> Bool #

(>=) :: Int -> Int -> Bool #

max :: Int -> Int -> Int #

min :: Int -> Int -> Int #

Additive Int Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

(+) :: Int -> Int -> Int Source #

zero :: Int Source #

Subtractive Int Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

negate :: Int -> Int Source #

(-) :: Int -> Int -> Int Source #

BoundedJoinSemiLattice Int Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

bottom :: Int Source #

BoundedMeetSemiLattice Int Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

top :: Int Source #

JoinSemiLattice Int Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(\/) :: Int -> Int -> Int Source #

MeetSemiLattice Int Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(/\) :: Int -> Int -> Int Source #

Basis Int Source # 
Instance details

Defined in NumHask.Algebra.Metric

Associated Types

type Mag Int Source #

type Base Int Source #

Epsilon Int Source #

0

Instance details

Defined in NumHask.Algebra.Metric

Methods

epsilon :: Int Source #

Multiplicative Int Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

(*) :: Int -> Int -> Int Source #

one :: Int Source #

InvolutiveRing Int Source # 
Instance details

Defined in NumHask.Algebra.Ring

Methods

adj :: Int -> Int Source #

FromInteger Int Source # 
Instance details

Defined in NumHask.Data.Integral

Integral Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

div :: Int -> Int -> Int Source #

mod :: Int -> Int -> Int Source #

divMod :: Int -> Int -> (Int, Int) Source #

quot :: Int -> Int -> Int Source #

rem :: Int -> Int -> Int Source #

quotRem :: Int -> Int -> (Int, Int) Source #

FromIntegral Int16 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int32 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int64 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int8 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word16 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word32 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word64 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word8 Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Integer Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Natural Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Double Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Float Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

fromIntegral :: Int -> Int Source #

FromIntegral Word Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int16 Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Int16 -> Int Source #

ToIntegral Int32 Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Int32 -> Int Source #

ToIntegral Int64 Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Int64 -> Int Source #

ToIntegral Int8 Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Int8 -> Int Source #

ToIntegral Word16 Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word32 Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word64 Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word8 Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Word8 -> Int Source #

ToIntegral Integer Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Natural Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Int -> Int Source #

ToIntegral Word Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Word -> Int Source #

ToRatio Int Integer Source # 
Instance details

Defined in NumHask.Data.Rational

Generic1 (URec Int :: k -> Type) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep1 (URec Int) :: k -> Type #

Methods

from1 :: forall (a :: k0). URec Int a -> Rep1 (URec Int) a #

to1 :: forall (a :: k0). Rep1 (URec Int) a -> URec Int a #

Foldable (UInt :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UInt m -> m #

foldMap :: Monoid m => (a -> m) -> UInt a -> m #

foldMap' :: Monoid m => (a -> m) -> UInt a -> m #

foldr :: (a -> b -> b) -> b -> UInt a -> b #

foldr' :: (a -> b -> b) -> b -> UInt a -> b #

foldl :: (b -> a -> b) -> b -> UInt a -> b #

foldl' :: (b -> a -> b) -> b -> UInt a -> b #

foldr1 :: (a -> a -> a) -> UInt a -> a #

foldl1 :: (a -> a -> a) -> UInt a -> a #

toList :: UInt a -> [a] #

null :: UInt a -> Bool #

length :: UInt a -> Int #

elem :: Eq a => a -> UInt a -> Bool #

maximum :: Ord a => UInt a -> a #

minimum :: Ord a => UInt a -> a #

sum :: Num a => UInt a -> a #

product :: Num a => UInt a -> a #

Traversable (UInt :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UInt a -> f (UInt b) #

sequenceA :: Applicative f => UInt (f a) -> f (UInt a) #

mapM :: Monad m => (a -> m b) -> UInt a -> m (UInt b) #

sequence :: Monad m => UInt (m a) -> m (UInt a) #

Functor (URec Int :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Int a -> URec Int b #

(<$) :: a -> URec Int b -> URec Int a #

Generic (URec Int p) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep (URec Int p) :: Type -> Type #

Methods

from :: URec Int p -> Rep (URec Int p) x #

to :: Rep (URec Int p) x -> URec Int p #

Show (URec Int p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Int p -> ShowS #

show :: URec Int p -> String #

showList :: [URec Int p] -> ShowS #

Eq (URec Int p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Int p -> URec Int p -> Bool #

(/=) :: URec Int p -> URec Int p -> Bool #

Ord (URec Int p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Int p -> URec Int p -> Ordering #

(<) :: URec Int p -> URec Int p -> Bool #

(<=) :: URec Int p -> URec Int p -> Bool #

(>) :: URec Int p -> URec Int p -> Bool #

(>=) :: URec Int p -> URec Int p -> Bool #

max :: URec Int p -> URec Int p -> URec Int p #

min :: URec Int p -> URec Int p -> URec Int p #

type Base Int Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Base Int = Int
type Mag Int Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Mag Int = Int
data URec Int (p :: k)

Used for marking occurrences of Int#

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

data URec Int (p :: k) = UInt {}
type Rep1 (URec Int :: k -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep1 (URec Int :: k -> Type) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UInt" 'PrefixI 'True) (S1 ('MetaSel ('Just "uInt#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UInt :: k -> Type)))
type Rep (URec Int p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep (URec Int p) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UInt" 'PrefixI 'True) (S1 ('MetaSel ('Just "uInt#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UInt :: Type -> Type)))

data Integer #

Arbitrary precision integers. In contrast with fixed-size integral types such as Int, the Integer type represents the entire infinite range of integers.

Integers are stored in a kind of sign-magnitude form, hence do not expect two's complement form when using bit operations.

If the value is small (fit into an Int), IS constructor is used. Otherwise Integer and IN constructors are used to store a BigNat representing respectively the positive or the negative value magnitude.

Invariant: Integer and IN are used iff value doesn't fit in IS

Instances

Instances details
Data Integer

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Integer -> c Integer #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Integer #

toConstr :: Integer -> Constr #

dataTypeOf :: Integer -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Integer) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Integer) #

gmapT :: (forall b. Data b => b -> b) -> Integer -> Integer #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Integer -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Integer -> r #

gmapQ :: (forall d. Data d => d -> u) -> Integer -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Integer -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Integer -> m Integer #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Integer -> m Integer #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Integer -> m Integer #

Enum Integer

Since: base-2.1

Instance details

Defined in GHC.Enum

Num Integer

Since: base-2.1

Instance details

Defined in GHC.Num

Read Integer

Since: base-2.1

Instance details

Defined in GHC.Read

Integral Integer

Since: base-2.0.1

Instance details

Defined in GHC.Real

Real Integer

Since: base-2.0.1

Instance details

Defined in GHC.Real

Show Integer

Since: base-2.1

Instance details

Defined in GHC.Show

Eq Integer 
Instance details

Defined in GHC.Num.Integer

Methods

(==) :: Integer -> Integer -> Bool #

(/=) :: Integer -> Integer -> Bool #

Ord Integer 
Instance details

Defined in GHC.Num.Integer

Additive Integer Source # 
Instance details

Defined in NumHask.Algebra.Additive

Subtractive Integer Source # 
Instance details

Defined in NumHask.Algebra.Additive

JoinSemiLattice Integer Source # 
Instance details

Defined in NumHask.Algebra.Lattice

MeetSemiLattice Integer Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Basis Integer Source # 
Instance details

Defined in NumHask.Algebra.Metric

Associated Types

type Mag Integer Source #

type Base Integer Source #

Epsilon Integer Source # 
Instance details

Defined in NumHask.Algebra.Metric

Multiplicative Integer Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

InvolutiveRing Integer Source # 
Instance details

Defined in NumHask.Algebra.Ring

Methods

adj :: Integer -> Integer Source #

FromInteger Integer Source # 
Instance details

Defined in NumHask.Data.Integral

Integral Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int16 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int32 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int64 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int8 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word16 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word32 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word64 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word8 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Integer Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Integer Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Natural Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Double Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Float Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Int Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int16 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int32 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int64 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int8 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word16 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word32 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word64 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word8 Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Integer Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Integer Int Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Natural Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Int Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromRatio Rational Integer Source # 
Instance details

Defined in NumHask.Data.Rational

FromRatio Double Integer Source # 
Instance details

Defined in NumHask.Data.Rational

FromRatio Float Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Int16 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Int32 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Int64 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Int8 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Word16 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Word32 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Word64 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Word8 Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Integer Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Natural Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Double Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Float Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Int Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Word Integer Source # 
Instance details

Defined in NumHask.Data.Rational

FromRational (Ratio Integer) Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio (Ratio Integer) Integer Source # 
Instance details

Defined in NumHask.Data.Rational

type Base Integer Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Mag Integer Source # 
Instance details

Defined in NumHask.Algebra.Metric

data Double #

Double-precision floating point numbers. It is desirable that this type be at least equal in range and precision to the IEEE double-precision type.

Instances

Instances details
Data Double

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Double -> c Double #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Double #

toConstr :: Double -> Constr #

dataTypeOf :: Double -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Double) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Double) #

gmapT :: (forall b. Data b => b -> b) -> Double -> Double #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Double -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Double -> r #

gmapQ :: (forall d. Data d => d -> u) -> Double -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Double -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Double -> m Double #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Double -> m Double #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Double -> m Double #

Floating Double

Since: base-2.1

Instance details

Defined in GHC.Float

RealFloat Double

Since: base-2.1

Instance details

Defined in GHC.Float

Read Double

Since: base-2.1

Instance details

Defined in GHC.Read

Eq Double

Note that due to the presence of NaN, Double's Eq instance does not satisfy reflexivity.

>>> 0/0 == (0/0 :: Double)
False

Also note that Double's Eq instance does not satisfy substitutivity:

>>> 0 == (-0 :: Double)
True
>>> recip 0 == recip (-0 :: Double)
False
Instance details

Defined in GHC.Classes

Methods

(==) :: Double -> Double -> Bool #

(/=) :: Double -> Double -> Bool #

Ord Double

Note that due to the presence of NaN, Double's Ord instance does not satisfy reflexivity.

>>> 0/0 <= (0/0 :: Double)
False

Also note that, due to the same, Ord's operator interactions are not respected by Double's instance:

>>> (0/0 :: Double) > 1
False
>>> compare (0/0 :: Double) 1
GT
Instance details

Defined in GHC.Classes

Additive Double Source # 
Instance details

Defined in NumHask.Algebra.Additive

Subtractive Double Source # 
Instance details

Defined in NumHask.Algebra.Additive

ExpField Double Source # 
Instance details

Defined in NumHask.Algebra.Field

QuotientField Double Source # 
Instance details

Defined in NumHask.Algebra.Field

Associated Types

type Whole Double Source #

TrigField Double Source # 
Instance details

Defined in NumHask.Algebra.Field

BoundedJoinSemiLattice Double Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

bottom :: Double Source #

BoundedMeetSemiLattice Double Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

top :: Double Source #

JoinSemiLattice Double Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(\/) :: Double -> Double -> Double Source #

MeetSemiLattice Double Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(/\) :: Double -> Double -> Double Source #

Basis Double Source # 
Instance details

Defined in NumHask.Algebra.Metric

Associated Types

type Mag Double Source #

type Base Double Source #

Epsilon Double Source #

1e-14

Instance details

Defined in NumHask.Algebra.Metric

Divisive Double Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Multiplicative Double Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

InvolutiveRing Double Source # 
Instance details

Defined in NumHask.Algebra.Ring

Methods

adj :: Double -> Double Source #

FromInteger Double Source # 
Instance details

Defined in NumHask.Data.Integral

FromRational Double Source # 
Instance details

Defined in NumHask.Data.Rational

FromIntegral Double Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Double Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromRatio Double Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Double Integer Source # 
Instance details

Defined in NumHask.Data.Rational

Generic1 (URec Double :: k -> Type) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep1 (URec Double) :: k -> Type #

Methods

from1 :: forall (a :: k0). URec Double a -> Rep1 (URec Double) a #

to1 :: forall (a :: k0). Rep1 (URec Double) a -> URec Double a #

Foldable (UDouble :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UDouble m -> m #

foldMap :: Monoid m => (a -> m) -> UDouble a -> m #

foldMap' :: Monoid m => (a -> m) -> UDouble a -> m #

foldr :: (a -> b -> b) -> b -> UDouble a -> b #

foldr' :: (a -> b -> b) -> b -> UDouble a -> b #

foldl :: (b -> a -> b) -> b -> UDouble a -> b #

foldl' :: (b -> a -> b) -> b -> UDouble a -> b #

foldr1 :: (a -> a -> a) -> UDouble a -> a #

foldl1 :: (a -> a -> a) -> UDouble a -> a #

toList :: UDouble a -> [a] #

null :: UDouble a -> Bool #

length :: UDouble a -> Int #

elem :: Eq a => a -> UDouble a -> Bool #

maximum :: Ord a => UDouble a -> a #

minimum :: Ord a => UDouble a -> a #

sum :: Num a => UDouble a -> a #

product :: Num a => UDouble a -> a #

Traversable (UDouble :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UDouble a -> f (UDouble b) #

sequenceA :: Applicative f => UDouble (f a) -> f (UDouble a) #

mapM :: Monad m => (a -> m b) -> UDouble a -> m (UDouble b) #

sequence :: Monad m => UDouble (m a) -> m (UDouble a) #

QuotientField (Positive Double) Source # 
Instance details

Defined in NumHask.Data.Positive

Associated Types

type Whole (Positive Double) Source #

Functor (URec Double :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Double a -> URec Double b #

(<$) :: a -> URec Double b -> URec Double a #

Generic (URec Double p) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep (URec Double p) :: Type -> Type #

Methods

from :: URec Double p -> Rep (URec Double p) x #

to :: Rep (URec Double p) x -> URec Double p #

Show (URec Double p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Double p -> ShowS #

show :: URec Double p -> String #

showList :: [URec Double p] -> ShowS #

Eq (URec Double p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Double p -> URec Double p -> Bool #

(/=) :: URec Double p -> URec Double p -> Bool #

Ord (URec Double p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Double p -> URec Double p -> Ordering #

(<) :: URec Double p -> URec Double p -> Bool #

(<=) :: URec Double p -> URec Double p -> Bool #

(>) :: URec Double p -> URec Double p -> Bool #

(>=) :: URec Double p -> URec Double p -> Bool #

max :: URec Double p -> URec Double p -> URec Double p #

min :: URec Double p -> URec Double p -> URec Double p #

type Whole Double Source # 
Instance details

Defined in NumHask.Algebra.Field

type Base Double Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Mag Double Source # 
Instance details

Defined in NumHask.Algebra.Metric

data URec Double (p :: k)

Used for marking occurrences of Double#

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

data URec Double (p :: k) = UDouble {}
type Rep1 (URec Double :: k -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep1 (URec Double :: k -> Type) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UDouble" 'PrefixI 'True) (S1 ('MetaSel ('Just "uDouble#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UDouble :: k -> Type)))
type Whole (Positive Double) Source # 
Instance details

Defined in NumHask.Data.Positive

type Rep (URec Double p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep (URec Double p) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UDouble" 'PrefixI 'True) (S1 ('MetaSel ('Just "uDouble#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UDouble :: Type -> Type)))

data Float #

Single-precision floating point numbers. It is desirable that this type be at least equal in range and precision to the IEEE single-precision type.

Instances

Instances details
Data Float

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Float -> c Float #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Float #

toConstr :: Float -> Constr #

dataTypeOf :: Float -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Float) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Float) #

gmapT :: (forall b. Data b => b -> b) -> Float -> Float #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Float -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Float -> r #

gmapQ :: (forall d. Data d => d -> u) -> Float -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Float -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Float -> m Float #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Float -> m Float #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Float -> m Float #

Floating Float

Since: base-2.1

Instance details

Defined in GHC.Float

RealFloat Float

Since: base-2.1

Instance details

Defined in GHC.Float

Read Float

Since: base-2.1

Instance details

Defined in GHC.Read

Eq Float

Note that due to the presence of NaN, Float's Eq instance does not satisfy reflexivity.

>>> 0/0 == (0/0 :: Float)
False

Also note that Float's Eq instance does not satisfy extensionality:

>>> 0 == (-0 :: Float)
True
>>> recip 0 == recip (-0 :: Float)
False
Instance details

Defined in GHC.Classes

Methods

(==) :: Float -> Float -> Bool #

(/=) :: Float -> Float -> Bool #

Ord Float

Note that due to the presence of NaN, Float's Ord instance does not satisfy reflexivity.

>>> 0/0 <= (0/0 :: Float)
False

Also note that, due to the same, Ord's operator interactions are not respected by Float's instance:

>>> (0/0 :: Float) > 1
False
>>> compare (0/0 :: Float) 1
GT
Instance details

Defined in GHC.Classes

Methods

compare :: Float -> Float -> Ordering #

(<) :: Float -> Float -> Bool #

(<=) :: Float -> Float -> Bool #

(>) :: Float -> Float -> Bool #

(>=) :: Float -> Float -> Bool #

max :: Float -> Float -> Float #

min :: Float -> Float -> Float #

Additive Float Source # 
Instance details

Defined in NumHask.Algebra.Additive

Subtractive Float Source # 
Instance details

Defined in NumHask.Algebra.Additive

ExpField Float Source # 
Instance details

Defined in NumHask.Algebra.Field

QuotientField Float Source # 
Instance details

Defined in NumHask.Algebra.Field

Associated Types

type Whole Float Source #

TrigField Float Source # 
Instance details

Defined in NumHask.Algebra.Field

BoundedJoinSemiLattice Float Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

bottom :: Float Source #

BoundedMeetSemiLattice Float Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

top :: Float Source #

JoinSemiLattice Float Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(\/) :: Float -> Float -> Float Source #

MeetSemiLattice Float Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(/\) :: Float -> Float -> Float Source #

Basis Float Source # 
Instance details

Defined in NumHask.Algebra.Metric

Associated Types

type Mag Float Source #

type Base Float Source #

Epsilon Float Source #

1e-6

Instance details

Defined in NumHask.Algebra.Metric

Methods

epsilon :: Float Source #

Divisive Float Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Multiplicative Float Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

(*) :: Float -> Float -> Float Source #

one :: Float Source #

InvolutiveRing Float Source # 
Instance details

Defined in NumHask.Algebra.Ring

Methods

adj :: Float -> Float Source #

FromInteger Float Source # 
Instance details

Defined in NumHask.Data.Integral

FromRational Float Source # 
Instance details

Defined in NumHask.Data.Rational

FromIntegral Float Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Float Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromRatio Float Integer Source # 
Instance details

Defined in NumHask.Data.Rational

ToRatio Float Integer Source # 
Instance details

Defined in NumHask.Data.Rational

Generic1 (URec Float :: k -> Type) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep1 (URec Float) :: k -> Type #

Methods

from1 :: forall (a :: k0). URec Float a -> Rep1 (URec Float) a #

to1 :: forall (a :: k0). Rep1 (URec Float) a -> URec Float a #

Foldable (UFloat :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UFloat m -> m #

foldMap :: Monoid m => (a -> m) -> UFloat a -> m #

foldMap' :: Monoid m => (a -> m) -> UFloat a -> m #

foldr :: (a -> b -> b) -> b -> UFloat a -> b #

foldr' :: (a -> b -> b) -> b -> UFloat a -> b #

foldl :: (b -> a -> b) -> b -> UFloat a -> b #

foldl' :: (b -> a -> b) -> b -> UFloat a -> b #

foldr1 :: (a -> a -> a) -> UFloat a -> a #

foldl1 :: (a -> a -> a) -> UFloat a -> a #

toList :: UFloat a -> [a] #

null :: UFloat a -> Bool #

length :: UFloat a -> Int #

elem :: Eq a => a -> UFloat a -> Bool #

maximum :: Ord a => UFloat a -> a #

minimum :: Ord a => UFloat a -> a #

sum :: Num a => UFloat a -> a #

product :: Num a => UFloat a -> a #

Traversable (UFloat :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UFloat a -> f (UFloat b) #

sequenceA :: Applicative f => UFloat (f a) -> f (UFloat a) #

mapM :: Monad m => (a -> m b) -> UFloat a -> m (UFloat b) #

sequence :: Monad m => UFloat (m a) -> m (UFloat a) #

Functor (URec Float :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Float a -> URec Float b #

(<$) :: a -> URec Float b -> URec Float a #

Generic (URec Float p) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep (URec Float p) :: Type -> Type #

Methods

from :: URec Float p -> Rep (URec Float p) x #

to :: Rep (URec Float p) x -> URec Float p #

Show (URec Float p) 
Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Float p -> ShowS #

show :: URec Float p -> String #

showList :: [URec Float p] -> ShowS #

Eq (URec Float p) 
Instance details

Defined in GHC.Generics

Methods

(==) :: URec Float p -> URec Float p -> Bool #

(/=) :: URec Float p -> URec Float p -> Bool #

Ord (URec Float p) 
Instance details

Defined in GHC.Generics

Methods

compare :: URec Float p -> URec Float p -> Ordering #

(<) :: URec Float p -> URec Float p -> Bool #

(<=) :: URec Float p -> URec Float p -> Bool #

(>) :: URec Float p -> URec Float p -> Bool #

(>=) :: URec Float p -> URec Float p -> Bool #

max :: URec Float p -> URec Float p -> URec Float p #

min :: URec Float p -> URec Float p -> URec Float p #

type Whole Float Source # 
Instance details

Defined in NumHask.Algebra.Field

type Whole Float = Int
type Base Float Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Mag Float Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Mag Float = Float
data URec Float (p :: k)

Used for marking occurrences of Float#

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

data URec Float (p :: k) = UFloat {}
type Rep1 (URec Float :: k -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep1 (URec Float :: k -> Type) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UFloat" 'PrefixI 'True) (S1 ('MetaSel ('Just "uFloat#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UFloat :: k -> Type)))
type Rep (URec Float p) 
Instance details

Defined in GHC.Generics

type Rep (URec Float p) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UFloat" 'PrefixI 'True) (S1 ('MetaSel ('Just "uFloat#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UFloat :: Type -> Type)))

class Show a where #

Conversion of values to readable Strings.

Derived instances of Show have the following properties, which are compatible with derived instances of Read:

  • The result of show is a syntactically correct Haskell expression containing only constants, given the fixity declarations in force at the point where the type is declared. It contains only the constructor names defined in the data type, parentheses, and spaces. When labelled constructor fields are used, braces, commas, field names, and equal signs are also used.
  • If the constructor is defined to be an infix operator, then showsPrec will produce infix applications of the constructor.
  • the representation will be enclosed in parentheses if the precedence of the top-level constructor in x is less than d (associativity is ignored). Thus, if d is 0 then the result is never surrounded in parentheses; if d is 11 it is always surrounded in parentheses, unless it is an atomic expression.
  • If the constructor is defined using record syntax, then show will produce the record-syntax form, with the fields given in the same order as the original declaration.

For example, given the declarations

infixr 5 :^:
data Tree a =  Leaf a  |  Tree a :^: Tree a

the derived instance of Show is equivalent to

instance (Show a) => Show (Tree a) where

       showsPrec d (Leaf m) = showParen (d > app_prec) $
            showString "Leaf " . showsPrec (app_prec+1) m
         where app_prec = 10

       showsPrec d (u :^: v) = showParen (d > up_prec) $
            showsPrec (up_prec+1) u .
            showString " :^: "      .
            showsPrec (up_prec+1) v
         where up_prec = 5

Note that right-associativity of :^: is ignored. For example,

  • show (Leaf 1 :^: Leaf 2 :^: Leaf 3) produces the string "Leaf 1 :^: (Leaf 2 :^: Leaf 3)".

Minimal complete definition

showsPrec | show

Methods

showsPrec #

Arguments

:: Int

the operator precedence of the enclosing context (a number from 0 to 11). Function application has precedence 10.

-> a

the value to be converted to a String

-> ShowS 

Convert a value to a readable String.

showsPrec should satisfy the law

showsPrec d x r ++ s  ==  showsPrec d x (r ++ s)

Derived instances of Read and Show satisfy the following:

That is, readsPrec parses the string produced by showsPrec, and delivers the value that showsPrec started with.

show :: a -> String #

A specialised variant of showsPrec, using precedence context zero, and returning an ordinary String.

showList :: [a] -> ShowS #

The method showList is provided to allow the programmer to give a specialised way of showing lists of values. For example, this is used by the predefined Show instance of the Char type, where values of type String should be shown in double quotes, rather than between square brackets.

Instances

Instances details
Show NestedAtomically

Since: base-4.0

Instance details

Defined in Control.Exception.Base

Show NoMatchingContinuationPrompt

Since: base-4.18

Instance details

Defined in Control.Exception.Base

Show NoMethodError

Since: base-4.0

Instance details

Defined in Control.Exception.Base

Show NonTermination

Since: base-4.0

Instance details

Defined in Control.Exception.Base

Show PatternMatchFail

Since: base-4.0

Instance details

Defined in Control.Exception.Base

Show RecConError

Since: base-4.0

Instance details

Defined in Control.Exception.Base

Show RecSelError

Since: base-4.0

Instance details

Defined in Control.Exception.Base

Show RecUpdError

Since: base-4.0

Instance details

Defined in Control.Exception.Base

Show TypeError

Since: base-4.9.0.0

Instance details

Defined in Control.Exception.Base

Show Constr

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Show ConstrRep

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Show DataRep

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Show DataType

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Show Fixity

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Show All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> All -> ShowS #

show :: All -> String #

showList :: [All] -> ShowS #

Show Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> Any -> ShowS #

show :: Any -> String #

showList :: [Any] -> ShowS #

Show SomeTypeRep

Since: base-4.10.0.0

Instance details

Defined in Data.Typeable.Internal

Show Version

Since: base-2.1

Instance details

Defined in Data.Version

Show Void

Since: base-4.8.0.0

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Void -> ShowS #

show :: Void -> String #

showList :: [Void] -> ShowS #

Show ErrorCall

Since: base-4.0.0.0

Instance details

Defined in GHC.Exception

Show ArithException

Since: base-4.0.0.0

Instance details

Defined in GHC.Exception.Type

Show SomeException

Since: base-3.0

Instance details

Defined in GHC.Exception.Type

Show Associativity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Show DecidedStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Show Fixity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Show SourceStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Show SourceUnpackedness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Show MaskingState

Since: base-4.3.0.0

Instance details

Defined in GHC.IO

Show AllocationLimitExceeded

Since: base-4.7.1.0

Instance details

Defined in GHC.IO.Exception

Show ArrayException

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show AssertionFailed

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show AsyncException

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show BlockedIndefinitelyOnMVar

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show BlockedIndefinitelyOnSTM

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show CompactionFailed

Since: base-4.10.0.0

Instance details

Defined in GHC.IO.Exception

Show Deadlock

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show ExitCode 
Instance details

Defined in GHC.IO.Exception

Show FixIOException

Since: base-4.11.0.0

Instance details

Defined in GHC.IO.Exception

Show IOErrorType

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show IOException

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Show SomeAsyncException

Since: base-4.7.0.0

Instance details

Defined in GHC.IO.Exception

Show Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

showsPrec :: Int -> Int16 -> ShowS #

show :: Int16 -> String #

showList :: [Int16] -> ShowS #

Show Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

showsPrec :: Int -> Int32 -> ShowS #

show :: Int32 -> String #

showList :: [Int32] -> ShowS #

Show Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

showsPrec :: Int -> Int64 -> ShowS #

show :: Int64 -> String #

showList :: [Int64] -> ShowS #

Show Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

showsPrec :: Int -> Int8 -> ShowS #

show :: Int8 -> String #

showList :: [Int8] -> ShowS #

Show CCFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show ConcFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show DebugFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show DoCostCentres

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show DoHeapProfile

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show DoTrace

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show GCFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show GiveGCStats

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show IoSubSystem 
Instance details

Defined in GHC.RTS.Flags

Show MiscFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show ParFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show ProfFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show RTSFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show TickyFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show TraceFlags

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Show FractionalExponentBase 
Instance details

Defined in GHC.Real

Show CallStack

Since: base-4.9.0.0

Instance details

Defined in GHC.Show

Show SrcLoc

Since: base-4.9.0.0

Instance details

Defined in GHC.Show

Show Word16

Since: base-2.1

Instance details

Defined in GHC.Word

Show Word32

Since: base-2.1

Instance details

Defined in GHC.Word

Show Word64

Since: base-2.1

Instance details

Defined in GHC.Word

Show Word8

Since: base-2.1

Instance details

Defined in GHC.Word

Methods

showsPrec :: Int -> Word8 -> ShowS #

show :: Word8 -> String #

showList :: [Word8] -> ShowS #

Show Lexeme

Since: base-2.1

Instance details

Defined in Text.Read.Lex

Show Number

Since: base-4.6.0.0

Instance details

Defined in Text.Read.Lex

Show KindRep 
Instance details

Defined in GHC.Show

Show Module

Since: base-4.9.0.0

Instance details

Defined in GHC.Show

Show Ordering

Since: base-2.1

Instance details

Defined in GHC.Show

Show TrName

Since: base-4.9.0.0

Instance details

Defined in GHC.Show

Show TyCon

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> TyCon -> ShowS #

show :: TyCon -> String #

showList :: [TyCon] -> ShowS #

Show TypeLitSort

Since: base-4.11.0.0

Instance details

Defined in GHC.Show

Show NumHaskException Source # 
Instance details

Defined in NumHask.Exception

Show Integer

Since: base-2.1

Instance details

Defined in GHC.Show

Show Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Show

Show ()

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> () -> ShowS #

show :: () -> String #

showList :: [()] -> ShowS #

Show Bool

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Bool -> ShowS #

show :: Bool -> String #

showList :: [Bool] -> ShowS #

Show Char

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Char -> ShowS #

show :: Char -> String #

showList :: [Char] -> ShowS #

Show Int

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Int -> ShowS #

show :: Int -> String #

showList :: [Int] -> ShowS #

Show Levity

Since: base-4.15.0.0

Instance details

Defined in GHC.Show

Show RuntimeRep

Since: base-4.11.0.0

Instance details

Defined in GHC.Show

Show VecCount

Since: base-4.11.0.0

Instance details

Defined in GHC.Show

Show VecElem

Since: base-4.11.0.0

Instance details

Defined in GHC.Show

Show Word

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Word -> ShowS #

show :: Word -> String #

showList :: [Word] -> ShowS #

Show a => Show (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in Control.Applicative

Methods

showsPrec :: Int -> ZipList a -> ShowS #

show :: ZipList a -> String #

showList :: [ZipList a] -> ShowS #

Show a => Show (Identity a)

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

showsPrec :: Int -> Identity a -> ShowS #

show :: Identity a -> String #

showList :: [Identity a] -> ShowS #

Show a => Show (First a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

showsPrec :: Int -> First a -> ShowS #

show :: First a -> String #

showList :: [First a] -> ShowS #

Show a => Show (Last a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

showsPrec :: Int -> Last a -> ShowS #

show :: Last a -> String #

showList :: [Last a] -> ShowS #

Show a => Show (Down a)

This instance would be equivalent to the derived instances of the Down newtype if the getDown field were removed

Since: base-4.7.0.0

Instance details

Defined in Data.Ord

Methods

showsPrec :: Int -> Down a -> ShowS #

show :: Down a -> String #

showList :: [Down a] -> ShowS #

Show a => Show (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> First a -> ShowS #

show :: First a -> String #

showList :: [First a] -> ShowS #

Show a => Show (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> Last a -> ShowS #

show :: Last a -> String #

showList :: [Last a] -> ShowS #

Show a => Show (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> Max a -> ShowS #

show :: Max a -> String #

showList :: [Max a] -> ShowS #

Show a => Show (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> Min a -> ShowS #

show :: Min a -> String #

showList :: [Min a] -> ShowS #

Show m => Show (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Show a => Show (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> Dual a -> ShowS #

show :: Dual a -> String #

showList :: [Dual a] -> ShowS #

Show a => Show (Product a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> Product a -> ShowS #

show :: Product a -> String #

showList :: [Product a] -> ShowS #

Show a => Show (Sum a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> Sum a -> ShowS #

show :: Sum a -> String #

showList :: [Sum a] -> ShowS #

Show a => Show (NonEmpty a)

Since: base-4.11.0.0

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> NonEmpty a -> ShowS #

show :: NonEmpty a -> String #

showList :: [NonEmpty a] -> ShowS #

Show p => Show (Par1 p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> Par1 p -> ShowS #

show :: Par1 p -> String #

showList :: [Par1 p] -> ShowS #

Show (FunPtr a)

Since: base-2.1

Instance details

Defined in GHC.Ptr

Methods

showsPrec :: Int -> FunPtr a -> ShowS #

show :: FunPtr a -> String #

showList :: [FunPtr a] -> ShowS #

Show (Ptr a)

Since: base-2.1

Instance details

Defined in GHC.Ptr

Methods

showsPrec :: Int -> Ptr a -> ShowS #

show :: Ptr a -> String #

showList :: [Ptr a] -> ShowS #

Show a => Show (Ratio a)

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

showsPrec :: Int -> Ratio a -> ShowS #

show :: Ratio a -> String #

showList :: [Ratio a] -> ShowS #

Show a => Show (Sum a) Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

showsPrec :: Int -> Sum a -> ShowS #

show :: Sum a -> String #

showList :: [Sum a] -> ShowS #

Show a => Show (EuclideanPair a) Source # 
Instance details

Defined in NumHask.Algebra.Metric

Show a => Show (Polar a) Source # 
Instance details

Defined in NumHask.Algebra.Metric

Methods

showsPrec :: Int -> Polar a -> ShowS #

show :: Polar a -> String #

showList :: [Polar a] -> ShowS #

Show a => Show (Product a) Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

showsPrec :: Int -> Product a -> ShowS #

show :: Product a -> String #

showList :: [Product a] -> ShowS #

Show a => Show (Complex a) Source # 
Instance details

Defined in NumHask.Data.Complex

Methods

showsPrec :: Int -> Complex a -> ShowS #

show :: Complex a -> String #

showList :: [Complex a] -> ShowS #

Show a => Show (Positive a) Source # 
Instance details

Defined in NumHask.Data.Positive

Methods

showsPrec :: Int -> Positive a -> ShowS #

show :: Positive a -> String #

showList :: [Positive a] -> ShowS #

Show a => Show (Ratio a) Source # 
Instance details

Defined in NumHask.Data.Rational

Methods

showsPrec :: Int -> Ratio a -> ShowS #

show :: Ratio a -> String #

showList :: [Ratio a] -> ShowS #

Show a => Show (Wrapped a) Source # 
Instance details

Defined in NumHask.Data.Wrapped

Methods

showsPrec :: Int -> Wrapped a -> ShowS #

show :: Wrapped a -> String #

showList :: [Wrapped a] -> ShowS #

Show a => Show (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Maybe a -> ShowS #

show :: Maybe a -> String #

showList :: [Maybe a] -> ShowS #

Show a => Show (a)

Since: base-4.15

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a) -> ShowS #

show :: (a) -> String #

showList :: [(a)] -> ShowS #

Show a => Show [a]

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> [a] -> ShowS #

show :: [a] -> String #

showList :: [[a]] -> ShowS #

(Show a, Show b) => Show (Either a b)

Since: base-3.0

Instance details

Defined in Data.Either

Methods

showsPrec :: Int -> Either a b -> ShowS #

show :: Either a b -> String #

showList :: [Either a b] -> ShowS #

(Show a, Show b) => Show (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

showsPrec :: Int -> Arg a b -> ShowS #

show :: Arg a b -> String #

showList :: [Arg a b] -> ShowS #

Show (TypeRep a) 
Instance details

Defined in Data.Typeable.Internal

Methods

showsPrec :: Int -> TypeRep a -> ShowS #

show :: TypeRep a -> String #

showList :: [TypeRep a] -> ShowS #

Show (U1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> U1 p -> ShowS #

show :: U1 p -> String #

showList :: [U1 p] -> ShowS #

Show (V1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> V1 p -> ShowS #

show :: V1 p -> String #

showList :: [V1 p] -> ShowS #

(Show a, Show b) => Show (a, b)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b) -> ShowS #

show :: (a, b) -> String #

showList :: [(a, b)] -> ShowS #

Show a => Show (Const a b)

This instance would be equivalent to the derived instances of the Const newtype if the getConst field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Const

Methods

showsPrec :: Int -> Const a b -> ShowS #

show :: Const a b -> String #

showList :: [Const a b] -> ShowS #

Show (f a) => Show (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

showsPrec :: Int -> Ap f a -> ShowS #

show :: Ap f a -> String #

showList :: [Ap f a] -> ShowS #

Show (f a) => Show (Alt f a)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

showsPrec :: Int -> Alt f a -> ShowS #

show :: Alt f a -> String #

showList :: [Alt f a] -> ShowS #

Show (OrderingI a b) 
Instance details

Defined in Data.Type.Ord

Methods

showsPrec :: Int -> OrderingI a b -> ShowS #

show :: OrderingI a b -> String #

showList :: [OrderingI a b] -> ShowS #

Show (f p) => Show (Rec1 f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> Rec1 f p -> ShowS #

show :: Rec1 f p -> String #

showList :: [Rec1 f p] -> ShowS #

Show (URec Char p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Char p -> ShowS #

show :: URec Char p -> String #

showList :: [URec Char p] -> ShowS #

Show (URec Double p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Double p -> ShowS #

show :: URec Double p -> String #

showList :: [URec Double p] -> ShowS #

Show (URec Float p) 
Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Float p -> ShowS #

show :: URec Float p -> String #

showList :: [URec Float p] -> ShowS #

Show (URec Int p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Int p -> ShowS #

show :: URec Int p -> String #

showList :: [URec Int p] -> ShowS #

Show (URec Word p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Word p -> ShowS #

show :: URec Word p -> String #

showList :: [URec Word p] -> ShowS #

(Show a, Show b, Show c) => Show (a, b, c)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c) -> ShowS #

show :: (a, b, c) -> String #

showList :: [(a, b, c)] -> ShowS #

(Show (f p), Show (g p)) => Show ((f :*: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> (f :*: g) p -> ShowS #

show :: (f :*: g) p -> String #

showList :: [(f :*: g) p] -> ShowS #

(Show (f p), Show (g p)) => Show ((f :+: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> (f :+: g) p -> ShowS #

show :: (f :+: g) p -> String #

showList :: [(f :+: g) p] -> ShowS #

Show c => Show (K1 i c p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> K1 i c p -> ShowS #

show :: K1 i c p -> String #

showList :: [K1 i c p] -> ShowS #

(Show a, Show b, Show c, Show d) => Show (a, b, c, d)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d) -> ShowS #

show :: (a, b, c, d) -> String #

showList :: [(a, b, c, d)] -> ShowS #

Show (f (g p)) => Show ((f :.: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> (f :.: g) p -> ShowS #

show :: (f :.: g) p -> String #

showList :: [(f :.: g) p] -> ShowS #

Show (f p) => Show (M1 i c f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> M1 i c f p -> ShowS #

show :: M1 i c f p -> String #

showList :: [M1 i c f p] -> ShowS #

(Show a, Show b, Show c, Show d, Show e) => Show (a, b, c, d, e)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e) -> ShowS #

show :: (a, b, c, d, e) -> String #

showList :: [(a, b, c, d, e)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f) => Show (a, b, c, d, e, f)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f) -> ShowS #

show :: (a, b, c, d, e, f) -> String #

showList :: [(a, b, c, d, e, f)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g) => Show (a, b, c, d, e, f, g)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g) -> ShowS #

show :: (a, b, c, d, e, f, g) -> String #

showList :: [(a, b, c, d, e, f, g)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h) => Show (a, b, c, d, e, f, g, h)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h) -> ShowS #

show :: (a, b, c, d, e, f, g, h) -> String #

showList :: [(a, b, c, d, e, f, g, h)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i) => Show (a, b, c, d, e, f, g, h, i)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i) -> ShowS #

show :: (a, b, c, d, e, f, g, h, i) -> String #

showList :: [(a, b, c, d, e, f, g, h, i)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j) => Show (a, b, c, d, e, f, g, h, i, j)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j) -> ShowS #

show :: (a, b, c, d, e, f, g, h, i, j) -> String #

showList :: [(a, b, c, d, e, f, g, h, i, j)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k) => Show (a, b, c, d, e, f, g, h, i, j, k)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k) -> ShowS #

show :: (a, b, c, d, e, f, g, h, i, j, k) -> String #

showList :: [(a, b, c, d, e, f, g, h, i, j, k)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l) => Show (a, b, c, d, e, f, g, h, i, j, k, l)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l) -> ShowS #

show :: (a, b, c, d, e, f, g, h, i, j, k, l) -> String #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> ShowS #

show :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> String #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m, Show n) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> ShowS #

show :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> String #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] -> ShowS #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m, Show n, Show o) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> ShowS #

show :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> String #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] -> ShowS #

class Bounded a where #

The Bounded class is used to name the upper and lower limits of a type. Ord is not a superclass of Bounded since types that are not totally ordered may also have upper and lower bounds.

The Bounded class may be derived for any enumeration type; minBound is the first constructor listed in the data declaration and maxBound is the last. Bounded may also be derived for single-constructor datatypes whose constituent types are in Bounded.

Methods

minBound :: a #

maxBound :: a #

Instances

Instances details
Bounded All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

minBound :: All #

maxBound :: All #

Bounded Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

minBound :: Any #

maxBound :: Any #

Bounded Associativity

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Bounded DecidedStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Bounded SourceStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Bounded SourceUnpackedness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Bounded Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Bounded Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Bounded Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Bounded Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Bounded Word16

Since: base-2.1

Instance details

Defined in GHC.Word

Bounded Word32

Since: base-2.1

Instance details

Defined in GHC.Word

Bounded Word64

Since: base-2.1

Instance details

Defined in GHC.Word

Bounded Word8

Since: base-2.1

Instance details

Defined in GHC.Word

Bounded Ordering

Since: base-2.1

Instance details

Defined in GHC.Enum

Bounded ()

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: () #

maxBound :: () #

Bounded Bool

Since: base-2.1

Instance details

Defined in GHC.Enum

Bounded Char

Since: base-2.1

Instance details

Defined in GHC.Enum

Bounded Int

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: Int #

maxBound :: Int #

Bounded Levity

Since: base-4.16.0.0

Instance details

Defined in GHC.Enum

Bounded VecCount

Since: base-4.10.0.0

Instance details

Defined in GHC.Enum

Bounded VecElem

Since: base-4.10.0.0

Instance details

Defined in GHC.Enum

Bounded Word

Since: base-2.1

Instance details

Defined in GHC.Enum

Bounded a => Bounded (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Bounded a => Bounded (Down a)

Swaps minBound and maxBound of the underlying type.

Since: base-4.14.0.0

Instance details

Defined in Data.Ord

Methods

minBound :: Down a #

maxBound :: Down a #

Bounded a => Bounded (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

minBound :: First a #

maxBound :: First a #

Bounded a => Bounded (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

minBound :: Last a #

maxBound :: Last a #

Bounded a => Bounded (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

minBound :: Max a #

maxBound :: Max a #

Bounded a => Bounded (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

minBound :: Min a #

maxBound :: Min a #

Bounded m => Bounded (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Bounded a => Bounded (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

minBound :: Dual a #

maxBound :: Dual a #

Bounded a => Bounded (Product a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Bounded a => Bounded (Sum a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

minBound :: Sum a #

maxBound :: Sum a #

Bounded a => Bounded (a) 
Instance details

Defined in GHC.Enum

Methods

minBound :: (a) #

maxBound :: (a) #

(Bounded a, Bounded b) => Bounded (a, b)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b) #

maxBound :: (a, b) #

Bounded a => Bounded (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

minBound :: Const a b #

maxBound :: Const a b #

(Applicative f, Bounded a) => Bounded (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

minBound :: Ap f a #

maxBound :: Ap f a #

(Bounded a, Bounded b, Bounded c) => Bounded (a, b, c)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c) #

maxBound :: (a, b, c) #

(Bounded a, Bounded b, Bounded c, Bounded d) => Bounded (a, b, c, d)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d) #

maxBound :: (a, b, c, d) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e) => Bounded (a, b, c, d, e)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e) #

maxBound :: (a, b, c, d, e) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f) => Bounded (a, b, c, d, e, f)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f) #

maxBound :: (a, b, c, d, e, f) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g) => Bounded (a, b, c, d, e, f, g)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g) #

maxBound :: (a, b, c, d, e, f, g) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h) => Bounded (a, b, c, d, e, f, g, h)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h) #

maxBound :: (a, b, c, d, e, f, g, h) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h, Bounded i) => Bounded (a, b, c, d, e, f, g, h, i)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h, i) #

maxBound :: (a, b, c, d, e, f, g, h, i) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h, Bounded i, Bounded j) => Bounded (a, b, c, d, e, f, g, h, i, j)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h, i, j) #

maxBound :: (a, b, c, d, e, f, g, h, i, j) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h, Bounded i, Bounded j, Bounded k) => Bounded (a, b, c, d, e, f, g, h, i, j, k)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h, i, j, k) #

maxBound :: (a, b, c, d, e, f, g, h, i, j, k) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h, Bounded i, Bounded j, Bounded k, Bounded l) => Bounded (a, b, c, d, e, f, g, h, i, j, k, l)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h, i, j, k, l) #

maxBound :: (a, b, c, d, e, f, g, h, i, j, k, l) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h, Bounded i, Bounded j, Bounded k, Bounded l, Bounded m) => Bounded (a, b, c, d, e, f, g, h, i, j, k, l, m)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h, i, j, k, l, m) #

maxBound :: (a, b, c, d, e, f, g, h, i, j, k, l, m) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h, Bounded i, Bounded j, Bounded k, Bounded l, Bounded m, Bounded n) => Bounded (a, b, c, d, e, f, g, h, i, j, k, l, m, n)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

maxBound :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

(Bounded a, Bounded b, Bounded c, Bounded d, Bounded e, Bounded f, Bounded g, Bounded h, Bounded i, Bounded j, Bounded k, Bounded l, Bounded m, Bounded n, Bounded o) => Bounded (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

maxBound :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

class Enum a where #

Class Enum defines operations on sequentially ordered types.

The enumFrom... methods are used in Haskell's translation of arithmetic sequences.

Instances of Enum may be derived for any enumeration type (types whose constructors have no fields). The nullary constructors are assumed to be numbered left-to-right by fromEnum from 0 through n-1. See Chapter 10 of the Haskell Report for more details.

For any type that is an instance of class Bounded as well as Enum, the following should hold:

   enumFrom     x   = enumFromTo     x maxBound
   enumFromThen x y = enumFromThenTo x y bound
     where
       bound | fromEnum y >= fromEnum x = maxBound
             | otherwise                = minBound

Minimal complete definition

toEnum, fromEnum

Methods

succ :: a -> a #

the successor of a value. For numeric types, succ adds 1.

pred :: a -> a #

the predecessor of a value. For numeric types, pred subtracts 1.

toEnum :: Int -> a #

Convert from an Int.

fromEnum :: a -> Int #

Convert to an Int. It is implementation-dependent what fromEnum returns when applied to a value that is too large to fit in an Int.

enumFrom :: a -> [a] #

Used in Haskell's translation of [n..] with [n..] = enumFrom n, a possible implementation being enumFrom n = n : enumFrom (succ n). For example:

  • enumFrom 4 :: [Integer] = [4,5,6,7,...]
  • enumFrom 6 :: [Int] = [6,7,8,9,...,maxBound :: Int]

enumFromThen :: a -> a -> [a] #

Used in Haskell's translation of [n,n'..] with [n,n'..] = enumFromThen n n', a possible implementation being enumFromThen n n' = n : n' : worker (f x) (f x n'), worker s v = v : worker s (s v), x = fromEnum n' - fromEnum n and f n y | n > 0 = f (n - 1) (succ y) | n < 0 = f (n + 1) (pred y) | otherwise = y For example:

  • enumFromThen 4 6 :: [Integer] = [4,6,8,10...]
  • enumFromThen 6 2 :: [Int] = [6,2,-2,-6,...,minBound :: Int]

enumFromTo :: a -> a -> [a] #

Used in Haskell's translation of [n..m] with [n..m] = enumFromTo n m, a possible implementation being enumFromTo n m | n <= m = n : enumFromTo (succ n) m | otherwise = []. For example:

  • enumFromTo 6 10 :: [Int] = [6,7,8,9,10]
  • enumFromTo 42 1 :: [Integer] = []

enumFromThenTo :: a -> a -> a -> [a] #

Used in Haskell's translation of [n,n'..m] with [n,n'..m] = enumFromThenTo n n' m, a possible implementation being enumFromThenTo n n' m = worker (f x) (c x) n m, x = fromEnum n' - fromEnum n, c x = bool (>=) ((x 0) f n y | n > 0 = f (n - 1) (succ y) | n < 0 = f (n + 1) (pred y) | otherwise = y and worker s c v m | c v m = v : worker s c (s v) m | otherwise = [] For example:

  • enumFromThenTo 4 2 -6 :: [Integer] = [4,2,0,-2,-4,-6]
  • enumFromThenTo 6 8 2 :: [Int] = []

Instances

Instances details
Enum Associativity

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Enum DecidedStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Enum SourceStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Enum SourceUnpackedness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Enum Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Enum Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Enum Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Enum Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

succ :: Int8 -> Int8 #

pred :: Int8 -> Int8 #

toEnum :: Int -> Int8 #

fromEnum :: Int8 -> Int #

enumFrom :: Int8 -> [Int8] #

enumFromThen :: Int8 -> Int8 -> [Int8] #

enumFromTo :: Int8 -> Int8 -> [Int8] #

enumFromThenTo :: Int8 -> Int8 -> Int8 -> [Int8] #

Enum DoCostCentres

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Enum DoHeapProfile

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Enum DoTrace

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Enum GiveGCStats

Since: base-4.8.0.0

Instance details

Defined in GHC.RTS.Flags

Enum IoSubSystem

Since: base-4.9.0.0

Instance details

Defined in GHC.RTS.Flags

Enum Word16

Since: base-2.1

Instance details

Defined in GHC.Word

Enum Word32

Since: base-2.1

Instance details

Defined in GHC.Word

Enum Word64

Since: base-2.1

Instance details

Defined in GHC.Word

Enum Word8

Since: base-2.1

Instance details

Defined in GHC.Word

Enum Ordering

Since: base-2.1

Instance details

Defined in GHC.Enum

Enum Integer

Since: base-2.1

Instance details

Defined in GHC.Enum

Enum Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Enum

Enum ()

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: () -> () #

pred :: () -> () #

toEnum :: Int -> () #

fromEnum :: () -> Int #

enumFrom :: () -> [()] #

enumFromThen :: () -> () -> [()] #

enumFromTo :: () -> () -> [()] #

enumFromThenTo :: () -> () -> () -> [()] #

Enum Bool

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Bool -> Bool #

pred :: Bool -> Bool #

toEnum :: Int -> Bool #

fromEnum :: Bool -> Int #

enumFrom :: Bool -> [Bool] #

enumFromThen :: Bool -> Bool -> [Bool] #

enumFromTo :: Bool -> Bool -> [Bool] #

enumFromThenTo :: Bool -> Bool -> Bool -> [Bool] #

Enum Char

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Char -> Char #

pred :: Char -> Char #

toEnum :: Int -> Char #

fromEnum :: Char -> Int #

enumFrom :: Char -> [Char] #

enumFromThen :: Char -> Char -> [Char] #

enumFromTo :: Char -> Char -> [Char] #

enumFromThenTo :: Char -> Char -> Char -> [Char] #

Enum Int

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Int -> Int #

pred :: Int -> Int #

toEnum :: Int -> Int #

fromEnum :: Int -> Int #

enumFrom :: Int -> [Int] #

enumFromThen :: Int -> Int -> [Int] #

enumFromTo :: Int -> Int -> [Int] #

enumFromThenTo :: Int -> Int -> Int -> [Int] #

Enum Levity

Since: base-4.16.0.0

Instance details

Defined in GHC.Enum

Enum VecCount

Since: base-4.10.0.0

Instance details

Defined in GHC.Enum

Enum VecElem

Since: base-4.10.0.0

Instance details

Defined in GHC.Enum

Enum Word

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Word -> Word #

pred :: Word -> Word #

toEnum :: Int -> Word #

fromEnum :: Word -> Int #

enumFrom :: Word -> [Word] #

enumFromThen :: Word -> Word -> [Word] #

enumFromTo :: Word -> Word -> [Word] #

enumFromThenTo :: Word -> Word -> Word -> [Word] #

Enum a => Enum (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

(Enum a, Bounded a, Eq a) => Enum (Down a)

Swaps succ and pred of the underlying type.

Since: base-4.18.0.0

Instance details

Defined in Data.Ord

Methods

succ :: Down a -> Down a #

pred :: Down a -> Down a #

toEnum :: Int -> Down a #

fromEnum :: Down a -> Int #

enumFrom :: Down a -> [Down a] #

enumFromThen :: Down a -> Down a -> [Down a] #

enumFromTo :: Down a -> Down a -> [Down a] #

enumFromThenTo :: Down a -> Down a -> Down a -> [Down a] #

Enum a => Enum (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

succ :: First a -> First a #

pred :: First a -> First a #

toEnum :: Int -> First a #

fromEnum :: First a -> Int #

enumFrom :: First a -> [First a] #

enumFromThen :: First a -> First a -> [First a] #

enumFromTo :: First a -> First a -> [First a] #

enumFromThenTo :: First a -> First a -> First a -> [First a] #

Enum a => Enum (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

succ :: Last a -> Last a #

pred :: Last a -> Last a #

toEnum :: Int -> Last a #

fromEnum :: Last a -> Int #

enumFrom :: Last a -> [Last a] #

enumFromThen :: Last a -> Last a -> [Last a] #

enumFromTo :: Last a -> Last a -> [Last a] #

enumFromThenTo :: Last a -> Last a -> Last a -> [Last a] #

Enum a => Enum (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

succ :: Max a -> Max a #

pred :: Max a -> Max a #

toEnum :: Int -> Max a #

fromEnum :: Max a -> Int #

enumFrom :: Max a -> [Max a] #

enumFromThen :: Max a -> Max a -> [Max a] #

enumFromTo :: Max a -> Max a -> [Max a] #

enumFromThenTo :: Max a -> Max a -> Max a -> [Max a] #

Enum a => Enum (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

succ :: Min a -> Min a #

pred :: Min a -> Min a #

toEnum :: Int -> Min a #

fromEnum :: Min a -> Int #

enumFrom :: Min a -> [Min a] #

enumFromThen :: Min a -> Min a -> [Min a] #

enumFromTo :: Min a -> Min a -> [Min a] #

enumFromThenTo :: Min a -> Min a -> Min a -> [Min a] #

Enum a => Enum (WrappedMonoid a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Integral a => Enum (Ratio a)

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

succ :: Ratio a -> Ratio a #

pred :: Ratio a -> Ratio a #

toEnum :: Int -> Ratio a #

fromEnum :: Ratio a -> Int #

enumFrom :: Ratio a -> [Ratio a] #

enumFromThen :: Ratio a -> Ratio a -> [Ratio a] #

enumFromTo :: Ratio a -> Ratio a -> [Ratio a] #

enumFromThenTo :: Ratio a -> Ratio a -> Ratio a -> [Ratio a] #

Enum a => Enum (a) 
Instance details

Defined in GHC.Enum

Methods

succ :: (a) -> (a) #

pred :: (a) -> (a) #

toEnum :: Int -> (a) #

fromEnum :: (a) -> Int #

enumFrom :: (a) -> [(a)] #

enumFromThen :: (a) -> (a) -> [(a)] #

enumFromTo :: (a) -> (a) -> [(a)] #

enumFromThenTo :: (a) -> (a) -> (a) -> [(a)] #

Enum a => Enum (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

succ :: Const a b -> Const a b #

pred :: Const a b -> Const a b #

toEnum :: Int -> Const a b #

fromEnum :: Const a b -> Int #

enumFrom :: Const a b -> [Const a b] #

enumFromThen :: Const a b -> Const a b -> [Const a b] #

enumFromTo :: Const a b -> Const a b -> [Const a b] #

enumFromThenTo :: Const a b -> Const a b -> Const a b -> [Const a b] #

Enum (f a) => Enum (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

succ :: Ap f a -> Ap f a #

pred :: Ap f a -> Ap f a #

toEnum :: Int -> Ap f a #

fromEnum :: Ap f a -> Int #

enumFrom :: Ap f a -> [Ap f a] #

enumFromThen :: Ap f a -> Ap f a -> [Ap f a] #

enumFromTo :: Ap f a -> Ap f a -> [Ap f a] #

enumFromThenTo :: Ap f a -> Ap f a -> Ap f a -> [Ap f a] #

Enum (f a) => Enum (Alt f a)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

succ :: Alt f a -> Alt f a #

pred :: Alt f a -> Alt f a #

toEnum :: Int -> Alt f a #

fromEnum :: Alt f a -> Int #

enumFrom :: Alt f a -> [Alt f a] #

enumFromThen :: Alt f a -> Alt f a -> [Alt f a] #

enumFromTo :: Alt f a -> Alt f a -> [Alt f a] #

enumFromThenTo :: Alt f a -> Alt f a -> Alt f a -> [Alt f a] #

class (Real a, Fractional a) => RealFrac a #

Extracting components of fractions.

Minimal complete definition

properFraction

Instances

Instances details
RealFrac a => RealFrac (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Methods

properFraction :: Integral b => Identity a -> (b, Identity a) #

truncate :: Integral b => Identity a -> b #

round :: Integral b => Identity a -> b #

ceiling :: Integral b => Identity a -> b #

floor :: Integral b => Identity a -> b #

RealFrac a => RealFrac (Down a)

Since: base-4.14.0.0

Instance details

Defined in Data.Ord

Methods

properFraction :: Integral b => Down a -> (b, Down a) #

truncate :: Integral b => Down a -> b #

round :: Integral b => Down a -> b #

ceiling :: Integral b => Down a -> b #

floor :: Integral b => Down a -> b #

Integral a => RealFrac (Ratio a)

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

properFraction :: Integral b => Ratio a -> (b, Ratio a) #

truncate :: Integral b => Ratio a -> b #

round :: Integral b => Ratio a -> b #

ceiling :: Integral b => Ratio a -> b #

floor :: Integral b => Ratio a -> b #

RealFrac a => RealFrac (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

properFraction :: Integral b0 => Const a b -> (b0, Const a b) #

truncate :: Integral b0 => Const a b -> b0 #

round :: Integral b0 => Const a b -> b0 #

ceiling :: Integral b0 => Const a b -> b0 #

floor :: Integral b0 => Const a b -> b0 #

class Read a where #

Parsing of Strings, producing values.

Derived instances of Read make the following assumptions, which derived instances of Show obey:

  • If the constructor is defined to be an infix operator, then the derived Read instance will parse only infix applications of the constructor (not the prefix form).
  • Associativity is not used to reduce the occurrence of parentheses, although precedence may be.
  • If the constructor is defined using record syntax, the derived Read will parse only the record-syntax form, and furthermore, the fields must be given in the same order as the original declaration.
  • The derived Read instance allows arbitrary Haskell whitespace between tokens of the input string. Extra parentheses are also allowed.

For example, given the declarations

infixr 5 :^:
data Tree a =  Leaf a  |  Tree a :^: Tree a

the derived instance of Read in Haskell 2010 is equivalent to

instance (Read a) => Read (Tree a) where

        readsPrec d r =  readParen (d > app_prec)
                         (\r -> [(Leaf m,t) |
                                 ("Leaf",s) <- lex r,
                                 (m,t) <- readsPrec (app_prec+1) s]) r

                      ++ readParen (d > up_prec)
                         (\r -> [(u:^:v,w) |
                                 (u,s) <- readsPrec (up_prec+1) r,
                                 (":^:",t) <- lex s,
                                 (v,w) <- readsPrec (up_prec+1) t]) r

          where app_prec = 10
                up_prec = 5

Note that right-associativity of :^: is unused.

The derived instance in GHC is equivalent to

instance (Read a) => Read (Tree a) where

        readPrec = parens $ (prec app_prec $ do
                                 Ident "Leaf" <- lexP
                                 m <- step readPrec
                                 return (Leaf m))

                     +++ (prec up_prec $ do
                                 u <- step readPrec
                                 Symbol ":^:" <- lexP
                                 v <- step readPrec
                                 return (u :^: v))

          where app_prec = 10
                up_prec = 5

        readListPrec = readListPrecDefault

Why do both readsPrec and readPrec exist, and why does GHC opt to implement readPrec in derived Read instances instead of readsPrec? The reason is that readsPrec is based on the ReadS type, and although ReadS is mentioned in the Haskell 2010 Report, it is not a very efficient parser data structure.

readPrec, on the other hand, is based on a much more efficient ReadPrec datatype (a.k.a "new-style parsers"), but its definition relies on the use of the RankNTypes language extension. Therefore, readPrec (and its cousin, readListPrec) are marked as GHC-only. Nevertheless, it is recommended to use readPrec instead of readsPrec whenever possible for the efficiency improvements it brings.

As mentioned above, derived Read instances in GHC will implement readPrec instead of readsPrec. The default implementations of readsPrec (and its cousin, readList) will simply use readPrec under the hood. If you are writing a Read instance by hand, it is recommended to write it like so:

instance Read T where
  readPrec     = ...
  readListPrec = readListPrecDefault

Minimal complete definition

readsPrec | readPrec

Methods

readsPrec #

Arguments

:: Int

the operator precedence of the enclosing context (a number from 0 to 11). Function application has precedence 10.

-> ReadS a 

attempts to parse a value from the front of the string, returning a list of (parsed value, remaining string) pairs. If there is no successful parse, the returned list is empty.

Derived instances of Read and Show satisfy the following:

That is, readsPrec parses the string produced by showsPrec, and delivers the value that showsPrec started with.

readList :: ReadS [a] #

The method readList is provided to allow the programmer to give a specialised way of parsing lists of values. For example, this is used by the predefined Read instance of the Char type, where values of type String should be are expected to use double quotes, rather than square brackets.

Instances

Instances details
Read All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Read Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Read Version

Since: base-2.1

Instance details

Defined in Data.Version

Read Void

Reading a Void value is always a parse error, considering Void as a data type with no constructors.

Since: base-4.8.0.0

Instance details

Defined in GHC.Read

Read Associativity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Read DecidedStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Read Fixity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Read SourceStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Read SourceUnpackedness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Read ExitCode 
Instance details

Defined in GHC.IO.Exception

Read Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Read Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Read Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Read Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Read GeneralCategory

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word16

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word32

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word64

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word8

Since: base-2.1

Instance details

Defined in GHC.Read

Read Lexeme

Since: base-2.1

Instance details

Defined in GHC.Read

Read Ordering

Since: base-2.1

Instance details

Defined in GHC.Read

Read Integer

Since: base-2.1

Instance details

Defined in GHC.Read

Read Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Read

Read ()

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS () #

readList :: ReadS [()] #

readPrec :: ReadPrec () #

readListPrec :: ReadPrec [()] #

Read Bool

Since: base-2.1

Instance details

Defined in GHC.Read

Read Char

Since: base-2.1

Instance details

Defined in GHC.Read

Read Double

Since: base-2.1

Instance details

Defined in GHC.Read

Read Float

Since: base-2.1

Instance details

Defined in GHC.Read

Read Int

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word

Since: base-4.5.0.0

Instance details

Defined in GHC.Read

Read a => Read (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in Control.Applicative

Read a => Read (Identity a)

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Read a => Read (First a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Read a => Read (Last a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Read a => Read (Down a)

This instance would be equivalent to the derived instances of the Down newtype if the getDown field were removed

Since: base-4.7.0.0

Instance details

Defined in Data.Ord

Read a => Read (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Read a => Read (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Read a => Read (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Read a => Read (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Read m => Read (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Read a => Read (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Read a => Read (Product a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Read a => Read (Sum a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Read a => Read (NonEmpty a)

Since: base-4.11.0.0

Instance details

Defined in GHC.Read

Read p => Read (Par1 p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

(Integral a, Read a) => Read (Ratio a)

Since: base-2.1

Instance details

Defined in GHC.Read

Read a => Read (Complex a) Source # 
Instance details

Defined in NumHask.Data.Complex

Read a => Read (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Read

Read a => Read (a)

Since: base-4.15

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a) #

readList :: ReadS [(a)] #

readPrec :: ReadPrec (a) #

readListPrec :: ReadPrec [(a)] #

Read a => Read [a]

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS [a] #

readList :: ReadS [[a]] #

readPrec :: ReadPrec [a] #

readListPrec :: ReadPrec [[a]] #

(Read a, Read b) => Read (Either a b)

Since: base-3.0

Instance details

Defined in Data.Either

(Read a, Read b) => Read (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

readsPrec :: Int -> ReadS (Arg a b) #

readList :: ReadS [Arg a b] #

readPrec :: ReadPrec (Arg a b) #

readListPrec :: ReadPrec [Arg a b] #

(Ix a, Read a, Read b) => Read (Array a b)

Since: base-2.1

Instance details

Defined in GHC.Read

Read (U1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Read (V1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

(Read a, Read b) => Read (a, b)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b) #

readList :: ReadS [(a, b)] #

readPrec :: ReadPrec (a, b) #

readListPrec :: ReadPrec [(a, b)] #

Read a => Read (Const a b)

This instance would be equivalent to the derived instances of the Const newtype if the getConst field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Const

Read (f a) => Read (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

readsPrec :: Int -> ReadS (Ap f a) #

readList :: ReadS [Ap f a] #

readPrec :: ReadPrec (Ap f a) #

readListPrec :: ReadPrec [Ap f a] #

Read (f a) => Read (Alt f a)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

readsPrec :: Int -> ReadS (Alt f a) #

readList :: ReadS [Alt f a] #

readPrec :: ReadPrec (Alt f a) #

readListPrec :: ReadPrec [Alt f a] #

Read (f p) => Read (Rec1 f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS (Rec1 f p) #

readList :: ReadS [Rec1 f p] #

readPrec :: ReadPrec (Rec1 f p) #

readListPrec :: ReadPrec [Rec1 f p] #

(Read a, Read b, Read c) => Read (a, b, c)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c) #

readList :: ReadS [(a, b, c)] #

readPrec :: ReadPrec (a, b, c) #

readListPrec :: ReadPrec [(a, b, c)] #

(Read (f p), Read (g p)) => Read ((f :*: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS ((f :*: g) p) #

readList :: ReadS [(f :*: g) p] #

readPrec :: ReadPrec ((f :*: g) p) #

readListPrec :: ReadPrec [(f :*: g) p] #

(Read (f p), Read (g p)) => Read ((f :+: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS ((f :+: g) p) #

readList :: ReadS [(f :+: g) p] #

readPrec :: ReadPrec ((f :+: g) p) #

readListPrec :: ReadPrec [(f :+: g) p] #

Read c => Read (K1 i c p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS (K1 i c p) #

readList :: ReadS [K1 i c p] #

readPrec :: ReadPrec (K1 i c p) #

readListPrec :: ReadPrec [K1 i c p] #

(Read a, Read b, Read c, Read d) => Read (a, b, c, d)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d) #

readList :: ReadS [(a, b, c, d)] #

readPrec :: ReadPrec (a, b, c, d) #

readListPrec :: ReadPrec [(a, b, c, d)] #

Read (f (g p)) => Read ((f :.: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS ((f :.: g) p) #

readList :: ReadS [(f :.: g) p] #

readPrec :: ReadPrec ((f :.: g) p) #

readListPrec :: ReadPrec [(f :.: g) p] #

Read (f p) => Read (M1 i c f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS (M1 i c f p) #

readList :: ReadS [M1 i c f p] #

readPrec :: ReadPrec (M1 i c f p) #

readListPrec :: ReadPrec [M1 i c f p] #

(Read a, Read b, Read c, Read d, Read e) => Read (a, b, c, d, e)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e) #

readList :: ReadS [(a, b, c, d, e)] #

readPrec :: ReadPrec (a, b, c, d, e) #

readListPrec :: ReadPrec [(a, b, c, d, e)] #

(Read a, Read b, Read c, Read d, Read e, Read f) => Read (a, b, c, d, e, f)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f) #

readList :: ReadS [(a, b, c, d, e, f)] #

readPrec :: ReadPrec (a, b, c, d, e, f) #

readListPrec :: ReadPrec [(a, b, c, d, e, f)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g) => Read (a, b, c, d, e, f, g)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g) #

readList :: ReadS [(a, b, c, d, e, f, g)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h) => Read (a, b, c, d, e, f, g, h)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h) #

readList :: ReadS [(a, b, c, d, e, f, g, h)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i) => Read (a, b, c, d, e, f, g, h, i)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j) => Read (a, b, c, d, e, f, g, h, i, j)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k) => Read (a, b, c, d, e, f, g, h, i, j, k)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l) => Read (a, b, c, d, e, f, g, h, i, j, k, l)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l, Read m) => Read (a, b, c, d, e, f, g, h, i, j, k, l, m)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l, m) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l, m)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l, m) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l, m)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l, Read m, Read n) => Read (a, b, c, d, e, f, g, h, i, j, k, l, m, n)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l, Read m, Read n, Read o) => Read (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] #

data IO a #

A value of type IO a is a computation which, when performed, does some I/O before returning a value of type a.

There is really only one way to "perform" an I/O action: bind it to Main.main in your program. When your program is run, the I/O will be performed. It isn't possible to perform I/O from an arbitrary function, unless that function is itself in the IO monad and called at some point, directly or indirectly, from Main.main.

IO is a monad, so IO actions can be combined using either the do-notation or the >> and >>= operations from the Monad class.

Instances

Instances details
MonadFail IO

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fail

Methods

fail :: String -> IO a #

Alternative IO

Takes the first non-throwing IO action's result. empty throws an exception.

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

empty :: IO a #

(<|>) :: IO a -> IO a -> IO a #

some :: IO a -> IO [a] #

many :: IO a -> IO [a] #

Applicative IO

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> IO a #

(<*>) :: IO (a -> b) -> IO a -> IO b #

liftA2 :: (a -> b -> c) -> IO a -> IO b -> IO c #

(*>) :: IO a -> IO b -> IO b #

(<*) :: IO a -> IO b -> IO a #

Functor IO

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> IO a -> IO b #

(<$) :: a -> IO b -> IO a #

Monad IO

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

(>>=) :: IO a -> (a -> IO b) -> IO b #

(>>) :: IO a -> IO b -> IO b #

return :: a -> IO a #

MonadPlus IO

Takes the first non-throwing IO action's result. mzero throws an exception.

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

mzero :: IO a #

mplus :: IO a -> IO a -> IO a #

Monoid a => Monoid (IO a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

mempty :: IO a #

mappend :: IO a -> IO a -> IO a #

mconcat :: [IO a] -> IO a #

Semigroup a => Semigroup (IO a)

Since: base-4.10.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: IO a -> IO a -> IO a #

sconcat :: NonEmpty (IO a) -> IO a #

stimes :: Integral b => b -> IO a -> IO a #

class Eq a => Ord a where #

The Ord class is used for totally ordered datatypes.

Instances of Ord can be derived for any user-defined datatype whose constituent types are in Ord. The declared order of the constructors in the data declaration determines the ordering in derived Ord instances. The Ordering datatype allows a single comparison to determine the precise ordering of two objects.

Ord, as defined by the Haskell report, implements a total order and has the following properties:

Comparability
x <= y || y <= x = True
Transitivity
if x <= y && y <= z = True, then x <= z = True
Reflexivity
x <= x = True
Antisymmetry
if x <= y && y <= x = True, then x == y = True

The following operator interactions are expected to hold:

  1. x >= y = y <= x
  2. x < y = x <= y && x /= y
  3. x > y = y < x
  4. x < y = compare x y == LT
  5. x > y = compare x y == GT
  6. x == y = compare x y == EQ
  7. min x y == if x <= y then x else y = True
  8. max x y == if x >= y then x else y = True

Note that (7.) and (8.) do not require min and max to return either of their arguments. The result is merely required to equal one of the arguments in terms of (==).

Minimal complete definition: either compare or <=. Using compare can be more efficient for complex types.

Minimal complete definition

compare | (<=)

Methods

compare :: a -> a -> Ordering #

(<) :: a -> a -> Bool infix 4 #

(<=) :: a -> a -> Bool infix 4 #

(>) :: a -> a -> Bool infix 4 #

(>=) :: a -> a -> Bool infix 4 #

max :: a -> a -> a #

min :: a -> a -> a #

Instances

Instances details
Ord All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: All -> All -> Ordering #

(<) :: All -> All -> Bool #

(<=) :: All -> All -> Bool #

(>) :: All -> All -> Bool #

(>=) :: All -> All -> Bool #

max :: All -> All -> All #

min :: All -> All -> All #

Ord Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: Any -> Any -> Ordering #

(<) :: Any -> Any -> Bool #

(<=) :: Any -> Any -> Bool #

(>) :: Any -> Any -> Bool #

(>=) :: Any -> Any -> Bool #

max :: Any -> Any -> Any #

min :: Any -> Any -> Any #

Ord SomeTypeRep 
Instance details

Defined in Data.Typeable.Internal

Ord Version

Since: base-2.1

Instance details

Defined in Data.Version

Ord Void

Since: base-4.8.0.0

Instance details

Defined in GHC.Base

Methods

compare :: Void -> Void -> Ordering #

(<) :: Void -> Void -> Bool #

(<=) :: Void -> Void -> Bool #

(>) :: Void -> Void -> Bool #

(>=) :: Void -> Void -> Bool #

max :: Void -> Void -> Void #

min :: Void -> Void -> Void #

Ord ErrorCall

Since: base-4.7.0.0

Instance details

Defined in GHC.Exception

Ord ArithException

Since: base-3.0

Instance details

Defined in GHC.Exception.Type

Ord Associativity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Ord DecidedStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Ord Fixity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Ord SourceStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Ord SourceUnpackedness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Ord ArrayException

Since: base-4.2.0.0

Instance details

Defined in GHC.IO.Exception

Ord AsyncException

Since: base-4.2.0.0

Instance details

Defined in GHC.IO.Exception

Ord ExitCode 
Instance details

Defined in GHC.IO.Exception

Ord Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

compare :: Int16 -> Int16 -> Ordering #

(<) :: Int16 -> Int16 -> Bool #

(<=) :: Int16 -> Int16 -> Bool #

(>) :: Int16 -> Int16 -> Bool #

(>=) :: Int16 -> Int16 -> Bool #

max :: Int16 -> Int16 -> Int16 #

min :: Int16 -> Int16 -> Int16 #

Ord Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

compare :: Int32 -> Int32 -> Ordering #

(<) :: Int32 -> Int32 -> Bool #

(<=) :: Int32 -> Int32 -> Bool #

(>) :: Int32 -> Int32 -> Bool #

(>=) :: Int32 -> Int32 -> Bool #

max :: Int32 -> Int32 -> Int32 #

min :: Int32 -> Int32 -> Int32 #

Ord Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

compare :: Int64 -> Int64 -> Ordering #

(<) :: Int64 -> Int64 -> Bool #

(<=) :: Int64 -> Int64 -> Bool #

(>) :: Int64 -> Int64 -> Bool #

(>=) :: Int64 -> Int64 -> Bool #

max :: Int64 -> Int64 -> Int64 #

min :: Int64 -> Int64 -> Int64 #

Ord Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

compare :: Int8 -> Int8 -> Ordering #

(<) :: Int8 -> Int8 -> Bool #

(<=) :: Int8 -> Int8 -> Bool #

(>) :: Int8 -> Int8 -> Bool #

(>=) :: Int8 -> Int8 -> Bool #

max :: Int8 -> Int8 -> Int8 #

min :: Int8 -> Int8 -> Int8 #

Ord Word16

Since: base-2.1

Instance details

Defined in GHC.Word

Ord Word32

Since: base-2.1

Instance details

Defined in GHC.Word

Ord Word64

Since: base-2.1

Instance details

Defined in GHC.Word

Ord Word8

Since: base-2.1

Instance details

Defined in GHC.Word

Methods

compare :: Word8 -> Word8 -> Ordering #

(<) :: Word8 -> Word8 -> Bool #

(<=) :: Word8 -> Word8 -> Bool #

(>) :: Word8 -> Word8 -> Bool #

(>=) :: Word8 -> Word8 -> Bool #

max :: Word8 -> Word8 -> Word8 #

min :: Word8 -> Word8 -> Word8 #

Ord BigNat 
Instance details

Defined in GHC.Num.BigNat

Ord Ordering 
Instance details

Defined in GHC.Classes

Ord TyCon 
Instance details

Defined in GHC.Classes

Methods

compare :: TyCon -> TyCon -> Ordering #

(<) :: TyCon -> TyCon -> Bool #

(<=) :: TyCon -> TyCon -> Bool #

(>) :: TyCon -> TyCon -> Bool #

(>=) :: TyCon -> TyCon -> Bool #

max :: TyCon -> TyCon -> TyCon #

min :: TyCon -> TyCon -> TyCon #

Ord Integer 
Instance details

Defined in GHC.Num.Integer

Ord Natural 
Instance details

Defined in GHC.Num.Natural

Ord () 
Instance details

Defined in GHC.Classes

Methods

compare :: () -> () -> Ordering #

(<) :: () -> () -> Bool #

(<=) :: () -> () -> Bool #

(>) :: () -> () -> Bool #

(>=) :: () -> () -> Bool #

max :: () -> () -> () #

min :: () -> () -> () #

Ord Bool 
Instance details

Defined in GHC.Classes

Methods

compare :: Bool -> Bool -> Ordering #

(<) :: Bool -> Bool -> Bool #

(<=) :: Bool -> Bool -> Bool #

(>) :: Bool -> Bool -> Bool #

(>=) :: Bool -> Bool -> Bool #

max :: Bool -> Bool -> Bool #

min :: Bool -> Bool -> Bool #

Ord Char 
Instance details

Defined in GHC.Classes

Methods

compare :: Char -> Char -> Ordering #

(<) :: Char -> Char -> Bool #

(<=) :: Char -> Char -> Bool #

(>) :: Char -> Char -> Bool #

(>=) :: Char -> Char -> Bool #

max :: Char -> Char -> Char #

min :: Char -> Char -> Char #

Ord Double

Note that due to the presence of NaN, Double's Ord instance does not satisfy reflexivity.

>>> 0/0 <= (0/0 :: Double)
False

Also note that, due to the same, Ord's operator interactions are not respected by Double's instance:

>>> (0/0 :: Double) > 1
False
>>> compare (0/0 :: Double) 1
GT
Instance details

Defined in GHC.Classes

Ord Float

Note that due to the presence of NaN, Float's Ord instance does not satisfy reflexivity.

>>> 0/0 <= (0/0 :: Float)
False

Also note that, due to the same, Ord's operator interactions are not respected by Float's instance:

>>> (0/0 :: Float) > 1
False
>>> compare (0/0 :: Float) 1
GT
Instance details

Defined in GHC.Classes

Methods

compare :: Float -> Float -> Ordering #

(<) :: Float -> Float -> Bool #

(<=) :: Float -> Float -> Bool #

(>) :: Float -> Float -> Bool #

(>=) :: Float -> Float -> Bool #

max :: Float -> Float -> Float #

min :: Float -> Float -> Float #

Ord Int 
Instance details

Defined in GHC.Classes

Methods

compare :: Int -> Int -> Ordering #

(<) :: Int -> Int -> Bool #

(<=) :: Int -> Int -> Bool #

(>) :: Int -> Int -> Bool #

(>=) :: Int -> Int -> Bool #

max :: Int -> Int -> Int #

min :: Int -> Int -> Int #

Ord Word 
Instance details

Defined in GHC.Classes

Methods

compare :: Word -> Word -> Ordering #

(<) :: Word -> Word -> Bool #

(<=) :: Word -> Word -> Bool #

(>) :: Word -> Word -> Bool #

(>=) :: Word -> Word -> Bool #

max :: Word -> Word -> Word #

min :: Word -> Word -> Word #

Ord a => Ord (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in Control.Applicative

Methods

compare :: ZipList a -> ZipList a -> Ordering #

(<) :: ZipList a -> ZipList a -> Bool #

(<=) :: ZipList a -> ZipList a -> Bool #

(>) :: ZipList a -> ZipList a -> Bool #

(>=) :: ZipList a -> ZipList a -> Bool #

max :: ZipList a -> ZipList a -> ZipList a #

min :: ZipList a -> ZipList a -> ZipList a #

Ord a => Ord (Identity a)

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

compare :: Identity a -> Identity a -> Ordering #

(<) :: Identity a -> Identity a -> Bool #

(<=) :: Identity a -> Identity a -> Bool #

(>) :: Identity a -> Identity a -> Bool #

(>=) :: Identity a -> Identity a -> Bool #

max :: Identity a -> Identity a -> Identity a #

min :: Identity a -> Identity a -> Identity a #

Ord a => Ord (First a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

compare :: First a -> First a -> Ordering #

(<) :: First a -> First a -> Bool #

(<=) :: First a -> First a -> Bool #

(>) :: First a -> First a -> Bool #

(>=) :: First a -> First a -> Bool #

max :: First a -> First a -> First a #

min :: First a -> First a -> First a #

Ord a => Ord (Last a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

compare :: Last a -> Last a -> Ordering #

(<) :: Last a -> Last a -> Bool #

(<=) :: Last a -> Last a -> Bool #

(>) :: Last a -> Last a -> Bool #

(>=) :: Last a -> Last a -> Bool #

max :: Last a -> Last a -> Last a #

min :: Last a -> Last a -> Last a #

Ord a => Ord (Down a)

Since: base-4.6.0.0

Instance details

Defined in Data.Ord

Methods

compare :: Down a -> Down a -> Ordering #

(<) :: Down a -> Down a -> Bool #

(<=) :: Down a -> Down a -> Bool #

(>) :: Down a -> Down a -> Bool #

(>=) :: Down a -> Down a -> Bool #

max :: Down a -> Down a -> Down a #

min :: Down a -> Down a -> Down a #

Ord a => Ord (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: First a -> First a -> Ordering #

(<) :: First a -> First a -> Bool #

(<=) :: First a -> First a -> Bool #

(>) :: First a -> First a -> Bool #

(>=) :: First a -> First a -> Bool #

max :: First a -> First a -> First a #

min :: First a -> First a -> First a #

Ord a => Ord (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: Last a -> Last a -> Ordering #

(<) :: Last a -> Last a -> Bool #

(<=) :: Last a -> Last a -> Bool #

(>) :: Last a -> Last a -> Bool #

(>=) :: Last a -> Last a -> Bool #

max :: Last a -> Last a -> Last a #

min :: Last a -> Last a -> Last a #

Ord a => Ord (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: Max a -> Max a -> Ordering #

(<) :: Max a -> Max a -> Bool #

(<=) :: Max a -> Max a -> Bool #

(>) :: Max a -> Max a -> Bool #

(>=) :: Max a -> Max a -> Bool #

max :: Max a -> Max a -> Max a #

min :: Max a -> Max a -> Max a #

Ord a => Ord (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: Min a -> Min a -> Ordering #

(<) :: Min a -> Min a -> Bool #

(<=) :: Min a -> Min a -> Bool #

(>) :: Min a -> Min a -> Bool #

(>=) :: Min a -> Min a -> Bool #

max :: Min a -> Min a -> Min a #

min :: Min a -> Min a -> Min a #

Ord m => Ord (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Ord a => Ord (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: Dual a -> Dual a -> Ordering #

(<) :: Dual a -> Dual a -> Bool #

(<=) :: Dual a -> Dual a -> Bool #

(>) :: Dual a -> Dual a -> Bool #

(>=) :: Dual a -> Dual a -> Bool #

max :: Dual a -> Dual a -> Dual a #

min :: Dual a -> Dual a -> Dual a #

Ord a => Ord (Product a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: Product a -> Product a -> Ordering #

(<) :: Product a -> Product a -> Bool #

(<=) :: Product a -> Product a -> Bool #

(>) :: Product a -> Product a -> Bool #

(>=) :: Product a -> Product a -> Bool #

max :: Product a -> Product a -> Product a #

min :: Product a -> Product a -> Product a #

Ord a => Ord (Sum a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: Sum a -> Sum a -> Ordering #

(<) :: Sum a -> Sum a -> Bool #

(<=) :: Sum a -> Sum a -> Bool #

(>) :: Sum a -> Sum a -> Bool #

(>=) :: Sum a -> Sum a -> Bool #

max :: Sum a -> Sum a -> Sum a #

min :: Sum a -> Sum a -> Sum a #

Ord a => Ord (NonEmpty a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

compare :: NonEmpty a -> NonEmpty a -> Ordering #

(<) :: NonEmpty a -> NonEmpty a -> Bool #

(<=) :: NonEmpty a -> NonEmpty a -> Bool #

(>) :: NonEmpty a -> NonEmpty a -> Bool #

(>=) :: NonEmpty a -> NonEmpty a -> Bool #

max :: NonEmpty a -> NonEmpty a -> NonEmpty a #

min :: NonEmpty a -> NonEmpty a -> NonEmpty a #

Ord p => Ord (Par1 p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: Par1 p -> Par1 p -> Ordering #

(<) :: Par1 p -> Par1 p -> Bool #

(<=) :: Par1 p -> Par1 p -> Bool #

(>) :: Par1 p -> Par1 p -> Bool #

(>=) :: Par1 p -> Par1 p -> Bool #

max :: Par1 p -> Par1 p -> Par1 p #

min :: Par1 p -> Par1 p -> Par1 p #

Ord (FunPtr a) 
Instance details

Defined in GHC.Ptr

Methods

compare :: FunPtr a -> FunPtr a -> Ordering #

(<) :: FunPtr a -> FunPtr a -> Bool #

(<=) :: FunPtr a -> FunPtr a -> Bool #

(>) :: FunPtr a -> FunPtr a -> Bool #

(>=) :: FunPtr a -> FunPtr a -> Bool #

max :: FunPtr a -> FunPtr a -> FunPtr a #

min :: FunPtr a -> FunPtr a -> FunPtr a #

Ord (Ptr a)

Since: base-2.1

Instance details

Defined in GHC.Ptr

Methods

compare :: Ptr a -> Ptr a -> Ordering #

(<) :: Ptr a -> Ptr a -> Bool #

(<=) :: Ptr a -> Ptr a -> Bool #

(>) :: Ptr a -> Ptr a -> Bool #

(>=) :: Ptr a -> Ptr a -> Bool #

max :: Ptr a -> Ptr a -> Ptr a #

min :: Ptr a -> Ptr a -> Ptr a #

Integral a => Ord (Ratio a)

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

compare :: Ratio a -> Ratio a -> Ordering #

(<) :: Ratio a -> Ratio a -> Bool #

(<=) :: Ratio a -> Ratio a -> Bool #

(>) :: Ratio a -> Ratio a -> Bool #

(>=) :: Ratio a -> Ratio a -> Bool #

max :: Ratio a -> Ratio a -> Ratio a #

min :: Ratio a -> Ratio a -> Ratio a #

Ord a => Ord (Sum a) Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

compare :: Sum a -> Sum a -> Ordering #

(<) :: Sum a -> Sum a -> Bool #

(<=) :: Sum a -> Sum a -> Bool #

(>) :: Sum a -> Sum a -> Bool #

(>=) :: Sum a -> Sum a -> Bool #

max :: Sum a -> Sum a -> Sum a #

min :: Sum a -> Sum a -> Sum a #

Ord a => Ord (Product a) Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

compare :: Product a -> Product a -> Ordering #

(<) :: Product a -> Product a -> Bool #

(<=) :: Product a -> Product a -> Bool #

(>) :: Product a -> Product a -> Bool #

(>=) :: Product a -> Product a -> Bool #

max :: Product a -> Product a -> Product a #

min :: Product a -> Product a -> Product a #

Ord a => Ord (Positive a) Source # 
Instance details

Defined in NumHask.Data.Positive

Methods

compare :: Positive a -> Positive a -> Ordering #

(<) :: Positive a -> Positive a -> Bool #

(<=) :: Positive a -> Positive a -> Bool #

(>) :: Positive a -> Positive a -> Bool #

(>=) :: Positive a -> Positive a -> Bool #

max :: Positive a -> Positive a -> Positive a #

min :: Positive a -> Positive a -> Positive a #

(Ord a, Integral a, EndoBased a, Subtractive a) => Ord (Ratio a) Source # 
Instance details

Defined in NumHask.Data.Rational

Methods

compare :: Ratio a -> Ratio a -> Ordering #

(<) :: Ratio a -> Ratio a -> Bool #

(<=) :: Ratio a -> Ratio a -> Bool #

(>) :: Ratio a -> Ratio a -> Bool #

(>=) :: Ratio a -> Ratio a -> Bool #

max :: Ratio a -> Ratio a -> Ratio a #

min :: Ratio a -> Ratio a -> Ratio a #

Ord a => Ord (Wrapped a) Source # 
Instance details

Defined in NumHask.Data.Wrapped

Methods

compare :: Wrapped a -> Wrapped a -> Ordering #

(<) :: Wrapped a -> Wrapped a -> Bool #

(<=) :: Wrapped a -> Wrapped a -> Bool #

(>) :: Wrapped a -> Wrapped a -> Bool #

(>=) :: Wrapped a -> Wrapped a -> Bool #

max :: Wrapped a -> Wrapped a -> Wrapped a #

min :: Wrapped a -> Wrapped a -> Wrapped a #

Ord a => Ord (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Maybe

Methods

compare :: Maybe a -> Maybe a -> Ordering #

(<) :: Maybe a -> Maybe a -> Bool #

(<=) :: Maybe a -> Maybe a -> Bool #

(>) :: Maybe a -> Maybe a -> Bool #

(>=) :: Maybe a -> Maybe a -> Bool #

max :: Maybe a -> Maybe a -> Maybe a #

min :: Maybe a -> Maybe a -> Maybe a #

Ord a => Ord (a) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a) -> (a) -> Ordering #

(<) :: (a) -> (a) -> Bool #

(<=) :: (a) -> (a) -> Bool #

(>) :: (a) -> (a) -> Bool #

(>=) :: (a) -> (a) -> Bool #

max :: (a) -> (a) -> (a) #

min :: (a) -> (a) -> (a) #

Ord a => Ord [a] 
Instance details

Defined in GHC.Classes

Methods

compare :: [a] -> [a] -> Ordering #

(<) :: [a] -> [a] -> Bool #

(<=) :: [a] -> [a] -> Bool #

(>) :: [a] -> [a] -> Bool #

(>=) :: [a] -> [a] -> Bool #

max :: [a] -> [a] -> [a] #

min :: [a] -> [a] -> [a] #

(Ord a, Ord b) => Ord (Either a b)

Since: base-2.1

Instance details

Defined in Data.Either

Methods

compare :: Either a b -> Either a b -> Ordering #

(<) :: Either a b -> Either a b -> Bool #

(<=) :: Either a b -> Either a b -> Bool #

(>) :: Either a b -> Either a b -> Bool #

(>=) :: Either a b -> Either a b -> Bool #

max :: Either a b -> Either a b -> Either a b #

min :: Either a b -> Either a b -> Either a b #

Ord a => Ord (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

compare :: Arg a b -> Arg a b -> Ordering #

(<) :: Arg a b -> Arg a b -> Bool #

(<=) :: Arg a b -> Arg a b -> Bool #

(>) :: Arg a b -> Arg a b -> Bool #

(>=) :: Arg a b -> Arg a b -> Bool #

max :: Arg a b -> Arg a b -> Arg a b #

min :: Arg a b -> Arg a b -> Arg a b #

Ord (TypeRep a)

Since: base-4.4.0.0

Instance details

Defined in Data.Typeable.Internal

Methods

compare :: TypeRep a -> TypeRep a -> Ordering #

(<) :: TypeRep a -> TypeRep a -> Bool #

(<=) :: TypeRep a -> TypeRep a -> Bool #

(>) :: TypeRep a -> TypeRep a -> Bool #

(>=) :: TypeRep a -> TypeRep a -> Bool #

max :: TypeRep a -> TypeRep a -> TypeRep a #

min :: TypeRep a -> TypeRep a -> TypeRep a #

Ord (U1 p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: U1 p -> U1 p -> Ordering #

(<) :: U1 p -> U1 p -> Bool #

(<=) :: U1 p -> U1 p -> Bool #

(>) :: U1 p -> U1 p -> Bool #

(>=) :: U1 p -> U1 p -> Bool #

max :: U1 p -> U1 p -> U1 p #

min :: U1 p -> U1 p -> U1 p #

Ord (V1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: V1 p -> V1 p -> Ordering #

(<) :: V1 p -> V1 p -> Bool #

(<=) :: V1 p -> V1 p -> Bool #

(>) :: V1 p -> V1 p -> Bool #

(>=) :: V1 p -> V1 p -> Bool #

max :: V1 p -> V1 p -> V1 p #

min :: V1 p -> V1 p -> V1 p #

(Ord a, Ord b) => Ord (a, b) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b) -> (a, b) -> Ordering #

(<) :: (a, b) -> (a, b) -> Bool #

(<=) :: (a, b) -> (a, b) -> Bool #

(>) :: (a, b) -> (a, b) -> Bool #

(>=) :: (a, b) -> (a, b) -> Bool #

max :: (a, b) -> (a, b) -> (a, b) #

min :: (a, b) -> (a, b) -> (a, b) #

Ord a => Ord (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

compare :: Const a b -> Const a b -> Ordering #

(<) :: Const a b -> Const a b -> Bool #

(<=) :: Const a b -> Const a b -> Bool #

(>) :: Const a b -> Const a b -> Bool #

(>=) :: Const a b -> Const a b -> Bool #

max :: Const a b -> Const a b -> Const a b #

min :: Const a b -> Const a b -> Const a b #

Ord (f a) => Ord (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

compare :: Ap f a -> Ap f a -> Ordering #

(<) :: Ap f a -> Ap f a -> Bool #

(<=) :: Ap f a -> Ap f a -> Bool #

(>) :: Ap f a -> Ap f a -> Bool #

(>=) :: Ap f a -> Ap f a -> Bool #

max :: Ap f a -> Ap f a -> Ap f a #

min :: Ap f a -> Ap f a -> Ap f a #

Ord (f a) => Ord (Alt f a)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

compare :: Alt f a -> Alt f a -> Ordering #

(<) :: Alt f a -> Alt f a -> Bool #

(<=) :: Alt f a -> Alt f a -> Bool #

(>) :: Alt f a -> Alt f a -> Bool #

(>=) :: Alt f a -> Alt f a -> Bool #

max :: Alt f a -> Alt f a -> Alt f a #

min :: Alt f a -> Alt f a -> Alt f a #

(Generic1 f, Ord (Rep1 f a)) => Ord (Generically1 f a)

Since: base-4.18.0.0

Instance details

Defined in GHC.Generics

Ord (f p) => Ord (Rec1 f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: Rec1 f p -> Rec1 f p -> Ordering #

(<) :: Rec1 f p -> Rec1 f p -> Bool #

(<=) :: Rec1 f p -> Rec1 f p -> Bool #

(>) :: Rec1 f p -> Rec1 f p -> Bool #

(>=) :: Rec1 f p -> Rec1 f p -> Bool #

max :: Rec1 f p -> Rec1 f p -> Rec1 f p #

min :: Rec1 f p -> Rec1 f p -> Rec1 f p #

Ord (URec (Ptr ()) p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec (Ptr ()) p -> URec (Ptr ()) p -> Ordering #

(<) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool #

(<=) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool #

(>) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool #

(>=) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool #

max :: URec (Ptr ()) p -> URec (Ptr ()) p -> URec (Ptr ()) p #

min :: URec (Ptr ()) p -> URec (Ptr ()) p -> URec (Ptr ()) p #

Ord (URec Char p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Char p -> URec Char p -> Ordering #

(<) :: URec Char p -> URec Char p -> Bool #

(<=) :: URec Char p -> URec Char p -> Bool #

(>) :: URec Char p -> URec Char p -> Bool #

(>=) :: URec Char p -> URec Char p -> Bool #

max :: URec Char p -> URec Char p -> URec Char p #

min :: URec Char p -> URec Char p -> URec Char p #

Ord (URec Double p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Double p -> URec Double p -> Ordering #

(<) :: URec Double p -> URec Double p -> Bool #

(<=) :: URec Double p -> URec Double p -> Bool #

(>) :: URec Double p -> URec Double p -> Bool #

(>=) :: URec Double p -> URec Double p -> Bool #

max :: URec Double p -> URec Double p -> URec Double p #

min :: URec Double p -> URec Double p -> URec Double p #

Ord (URec Float p) 
Instance details

Defined in GHC.Generics

Methods

compare :: URec Float p -> URec Float p -> Ordering #

(<) :: URec Float p -> URec Float p -> Bool #

(<=) :: URec Float p -> URec Float p -> Bool #

(>) :: URec Float p -> URec Float p -> Bool #

(>=) :: URec Float p -> URec Float p -> Bool #

max :: URec Float p -> URec Float p -> URec Float p #

min :: URec Float p -> URec Float p -> URec Float p #

Ord (URec Int p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Int p -> URec Int p -> Ordering #

(<) :: URec Int p -> URec Int p -> Bool #

(<=) :: URec Int p -> URec Int p -> Bool #

(>) :: URec Int p -> URec Int p -> Bool #

(>=) :: URec Int p -> URec Int p -> Bool #

max :: URec Int p -> URec Int p -> URec Int p #

min :: URec Int p -> URec Int p -> URec Int p #

Ord (URec Word p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Word p -> URec Word p -> Ordering #

(<) :: URec Word p -> URec Word p -> Bool #

(<=) :: URec Word p -> URec Word p -> Bool #

(>) :: URec Word p -> URec Word p -> Bool #

(>=) :: URec Word p -> URec Word p -> Bool #

max :: URec Word p -> URec Word p -> URec Word p #

min :: URec Word p -> URec Word p -> URec Word p #

(Ord a, Ord b, Ord c) => Ord (a, b, c) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c) -> (a, b, c) -> Ordering #

(<) :: (a, b, c) -> (a, b, c) -> Bool #

(<=) :: (a, b, c) -> (a, b, c) -> Bool #

(>) :: (a, b, c) -> (a, b, c) -> Bool #

(>=) :: (a, b, c) -> (a, b, c) -> Bool #

max :: (a, b, c) -> (a, b, c) -> (a, b, c) #

min :: (a, b, c) -> (a, b, c) -> (a, b, c) #

(Ord (f p), Ord (g p)) => Ord ((f :*: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: (f :*: g) p -> (f :*: g) p -> Ordering #

(<) :: (f :*: g) p -> (f :*: g) p -> Bool #

(<=) :: (f :*: g) p -> (f :*: g) p -> Bool #

(>) :: (f :*: g) p -> (f :*: g) p -> Bool #

(>=) :: (f :*: g) p -> (f :*: g) p -> Bool #

max :: (f :*: g) p -> (f :*: g) p -> (f :*: g) p #

min :: (f :*: g) p -> (f :*: g) p -> (f :*: g) p #

(Ord (f p), Ord (g p)) => Ord ((f :+: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: (f :+: g) p -> (f :+: g) p -> Ordering #

(<) :: (f :+: g) p -> (f :+: g) p -> Bool #

(<=) :: (f :+: g) p -> (f :+: g) p -> Bool #

(>) :: (f :+: g) p -> (f :+: g) p -> Bool #

(>=) :: (f :+: g) p -> (f :+: g) p -> Bool #

max :: (f :+: g) p -> (f :+: g) p -> (f :+: g) p #

min :: (f :+: g) p -> (f :+: g) p -> (f :+: g) p #

Ord c => Ord (K1 i c p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: K1 i c p -> K1 i c p -> Ordering #

(<) :: K1 i c p -> K1 i c p -> Bool #

(<=) :: K1 i c p -> K1 i c p -> Bool #

(>) :: K1 i c p -> K1 i c p -> Bool #

(>=) :: K1 i c p -> K1 i c p -> Bool #

max :: K1 i c p -> K1 i c p -> K1 i c p #

min :: K1 i c p -> K1 i c p -> K1 i c p #

(Ord a, Ord b, Ord c, Ord d) => Ord (a, b, c, d) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d) -> (a, b, c, d) -> Ordering #

(<) :: (a, b, c, d) -> (a, b, c, d) -> Bool #

(<=) :: (a, b, c, d) -> (a, b, c, d) -> Bool #

(>) :: (a, b, c, d) -> (a, b, c, d) -> Bool #

(>=) :: (a, b, c, d) -> (a, b, c, d) -> Bool #

max :: (a, b, c, d) -> (a, b, c, d) -> (a, b, c, d) #

min :: (a, b, c, d) -> (a, b, c, d) -> (a, b, c, d) #

Ord (f (g p)) => Ord ((f :.: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: (f :.: g) p -> (f :.: g) p -> Ordering #

(<) :: (f :.: g) p -> (f :.: g) p -> Bool #

(<=) :: (f :.: g) p -> (f :.: g) p -> Bool #

(>) :: (f :.: g) p -> (f :.: g) p -> Bool #

(>=) :: (f :.: g) p -> (f :.: g) p -> Bool #

max :: (f :.: g) p -> (f :.: g) p -> (f :.: g) p #

min :: (f :.: g) p -> (f :.: g) p -> (f :.: g) p #

Ord (f p) => Ord (M1 i c f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: M1 i c f p -> M1 i c f p -> Ordering #

(<) :: M1 i c f p -> M1 i c f p -> Bool #

(<=) :: M1 i c f p -> M1 i c f p -> Bool #

(>) :: M1 i c f p -> M1 i c f p -> Bool #

(>=) :: M1 i c f p -> M1 i c f p -> Bool #

max :: M1 i c f p -> M1 i c f p -> M1 i c f p #

min :: M1 i c f p -> M1 i c f p -> M1 i c f p #

(Ord a, Ord b, Ord c, Ord d, Ord e) => Ord (a, b, c, d, e) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e) -> (a, b, c, d, e) -> Ordering #

(<) :: (a, b, c, d, e) -> (a, b, c, d, e) -> Bool #

(<=) :: (a, b, c, d, e) -> (a, b, c, d, e) -> Bool #

(>) :: (a, b, c, d, e) -> (a, b, c, d, e) -> Bool #

(>=) :: (a, b, c, d, e) -> (a, b, c, d, e) -> Bool #

max :: (a, b, c, d, e) -> (a, b, c, d, e) -> (a, b, c, d, e) #

min :: (a, b, c, d, e) -> (a, b, c, d, e) -> (a, b, c, d, e) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f) => Ord (a, b, c, d, e, f) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> Ordering #

(<) :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> Bool #

(<=) :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> Bool #

(>) :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> Bool #

(>=) :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> Bool #

max :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> (a, b, c, d, e, f) #

min :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> (a, b, c, d, e, f) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g) => Ord (a, b, c, d, e, f, g) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> Ordering #

(<) :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> Bool #

(<=) :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> Bool #

(>) :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> Bool #

(>=) :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> Bool #

max :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) #

min :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h) => Ord (a, b, c, d, e, f, g, h) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> Bool #

(>) :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> Bool #

max :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) #

min :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i) => Ord (a, b, c, d, e, f, g, h, i) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> Bool #

(>) :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> Bool #

max :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) #

min :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j) => Ord (a, b, c, d, e, f, g, h, i, j) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> Bool #

(>) :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> Bool #

max :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) #

min :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k) => Ord (a, b, c, d, e, f, g, h, i, j, k) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> Bool #

(>) :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> Bool #

max :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) #

min :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l) => Ord (a, b, c, d, e, f, g, h, i, j, k, l) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> Bool #

(>) :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> Bool #

max :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) #

min :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l, Ord m) => Ord (a, b, c, d, e, f, g, h, i, j, k, l, m) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Bool #

(>) :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Bool #

max :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) #

min :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l, Ord m, Ord n) => Ord (a, b, c, d, e, f, g, h, i, j, k, l, m, n) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Bool #

(>) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Bool #

max :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

min :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l, Ord m, Ord n, Ord o) => Ord (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) 
Instance details

Defined in GHC.Classes

Methods

compare :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Ordering #

(<) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Bool #

(<=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Bool #

(>) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Bool #

(>=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Bool #

max :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

min :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

type String = [Char] #

A String is a list of characters. String constants in Haskell are values of type String.

See Data.List for operations on lists.

data Char #

The character type Char is an enumeration whose values represent Unicode (or equivalently ISO/IEC 10646) code points (i.e. characters, see http://www.unicode.org/ for details). This set extends the ISO 8859-1 (Latin-1) character set (the first 256 characters), which is itself an extension of the ASCII character set (the first 128 characters). A character literal in Haskell has type Char.

To convert a Char to or from the corresponding Int value defined by Unicode, use toEnum and fromEnum from the Enum class respectively (or equivalently ord and chr).

Instances

Instances details
Data Char

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Char -> c Char #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Char #

toConstr :: Char -> Constr #

dataTypeOf :: Char -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Char) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Char) #

gmapT :: (forall b. Data b => b -> b) -> Char -> Char #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Char -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Char -> r #

gmapQ :: (forall d. Data d => d -> u) -> Char -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Char -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Char -> m Char #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Char -> m Char #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Char -> m Char #

Bounded Char

Since: base-2.1

Instance details

Defined in GHC.Enum

Enum Char

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Char -> Char #

pred :: Char -> Char #

toEnum :: Int -> Char #

fromEnum :: Char -> Int #

enumFrom :: Char -> [Char] #

enumFromThen :: Char -> Char -> [Char] #

enumFromTo :: Char -> Char -> [Char] #

enumFromThenTo :: Char -> Char -> Char -> [Char] #

Read Char

Since: base-2.1

Instance details

Defined in GHC.Read

Show Char

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Char -> ShowS #

show :: Char -> String #

showList :: [Char] -> ShowS #

Eq Char 
Instance details

Defined in GHC.Classes

Methods

(==) :: Char -> Char -> Bool #

(/=) :: Char -> Char -> Bool #

Ord Char 
Instance details

Defined in GHC.Classes

Methods

compare :: Char -> Char -> Ordering #

(<) :: Char -> Char -> Bool #

(<=) :: Char -> Char -> Bool #

(>) :: Char -> Char -> Bool #

(>=) :: Char -> Char -> Bool #

max :: Char -> Char -> Char #

min :: Char -> Char -> Char #

Generic1 (URec Char :: k -> Type) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep1 (URec Char) :: k -> Type #

Methods

from1 :: forall (a :: k0). URec Char a -> Rep1 (URec Char) a #

to1 :: forall (a :: k0). Rep1 (URec Char) a -> URec Char a #

Foldable (UChar :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UChar m -> m #

foldMap :: Monoid m => (a -> m) -> UChar a -> m #

foldMap' :: Monoid m => (a -> m) -> UChar a -> m #

foldr :: (a -> b -> b) -> b -> UChar a -> b #

foldr' :: (a -> b -> b) -> b -> UChar a -> b #

foldl :: (b -> a -> b) -> b -> UChar a -> b #

foldl' :: (b -> a -> b) -> b -> UChar a -> b #

foldr1 :: (a -> a -> a) -> UChar a -> a #

foldl1 :: (a -> a -> a) -> UChar a -> a #

toList :: UChar a -> [a] #

null :: UChar a -> Bool #

length :: UChar a -> Int #

elem :: Eq a => a -> UChar a -> Bool #

maximum :: Ord a => UChar a -> a #

minimum :: Ord a => UChar a -> a #

sum :: Num a => UChar a -> a #

product :: Num a => UChar a -> a #

Traversable (UChar :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UChar a -> f (UChar b) #

sequenceA :: Applicative f => UChar (f a) -> f (UChar a) #

mapM :: Monad m => (a -> m b) -> UChar a -> m (UChar b) #

sequence :: Monad m => UChar (m a) -> m (UChar a) #

Functor (URec Char :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Char a -> URec Char b #

(<$) :: a -> URec Char b -> URec Char a #

Generic (URec Char p) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep (URec Char p) :: Type -> Type #

Methods

from :: URec Char p -> Rep (URec Char p) x #

to :: Rep (URec Char p) x -> URec Char p #

Show (URec Char p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Char p -> ShowS #

show :: URec Char p -> String #

showList :: [URec Char p] -> ShowS #

Eq (URec Char p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Char p -> URec Char p -> Bool #

(/=) :: URec Char p -> URec Char p -> Bool #

Ord (URec Char p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Char p -> URec Char p -> Ordering #

(<) :: URec Char p -> URec Char p -> Bool #

(<=) :: URec Char p -> URec Char p -> Bool #

(>) :: URec Char p -> URec Char p -> Bool #

(>=) :: URec Char p -> URec Char p -> Bool #

max :: URec Char p -> URec Char p -> URec Char p #

min :: URec Char p -> URec Char p -> URec Char p #

data URec Char (p :: k)

Used for marking occurrences of Char#

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

data URec Char (p :: k) = UChar {}
type Compare (a :: Char) (b :: Char) 
Instance details

Defined in Data.Type.Ord

type Compare (a :: Char) (b :: Char) = CmpChar a b
type Rep1 (URec Char :: k -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep1 (URec Char :: k -> Type) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UChar" 'PrefixI 'True) (S1 ('MetaSel ('Just "uChar#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UChar :: k -> Type)))
type Rep (URec Char p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep (URec Char p) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UChar" 'PrefixI 'True) (S1 ('MetaSel ('Just "uChar#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UChar :: Type -> Type)))

data Word #

A Word is an unsigned integral type, with the same size as Int.

Instances

Instances details
Data Word

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Word -> c Word #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Word #

toConstr :: Word -> Constr #

dataTypeOf :: Word -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Word) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Word) #

gmapT :: (forall b. Data b => b -> b) -> Word -> Word #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Word -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Word -> r #

gmapQ :: (forall d. Data d => d -> u) -> Word -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Word -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Word -> m Word #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Word -> m Word #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Word -> m Word #

Bounded Word

Since: base-2.1

Instance details

Defined in GHC.Enum

Enum Word

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Word -> Word #

pred :: Word -> Word #

toEnum :: Int -> Word #

fromEnum :: Word -> Int #

enumFrom :: Word -> [Word] #

enumFromThen :: Word -> Word -> [Word] #

enumFromTo :: Word -> Word -> [Word] #

enumFromThenTo :: Word -> Word -> Word -> [Word] #

Num Word

Since: base-2.1

Instance details

Defined in GHC.Num

Methods

(+) :: Word -> Word -> Word #

(-) :: Word -> Word -> Word #

(*) :: Word -> Word -> Word #

negate :: Word -> Word #

abs :: Word -> Word #

signum :: Word -> Word #

fromInteger :: Integer -> Word #

Read Word

Since: base-4.5.0.0

Instance details

Defined in GHC.Read

Integral Word

Since: base-2.1

Instance details

Defined in GHC.Real

Methods

quot :: Word -> Word -> Word #

rem :: Word -> Word -> Word #

div :: Word -> Word -> Word #

mod :: Word -> Word -> Word #

quotRem :: Word -> Word -> (Word, Word) #

divMod :: Word -> Word -> (Word, Word) #

toInteger :: Word -> Integer #

Real Word

Since: base-2.1

Instance details

Defined in GHC.Real

Methods

toRational :: Word -> Rational #

Show Word

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Word -> ShowS #

show :: Word -> String #

showList :: [Word] -> ShowS #

Eq Word 
Instance details

Defined in GHC.Classes

Methods

(==) :: Word -> Word -> Bool #

(/=) :: Word -> Word -> Bool #

Ord Word 
Instance details

Defined in GHC.Classes

Methods

compare :: Word -> Word -> Ordering #

(<) :: Word -> Word -> Bool #

(<=) :: Word -> Word -> Bool #

(>) :: Word -> Word -> Bool #

(>=) :: Word -> Word -> Bool #

max :: Word -> Word -> Word #

min :: Word -> Word -> Word #

Additive Word Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

(+) :: Word -> Word -> Word Source #

zero :: Word Source #

Subtractive Word Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

negate :: Word -> Word Source #

(-) :: Word -> Word -> Word Source #

BoundedJoinSemiLattice Word Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

bottom :: Word Source #

BoundedMeetSemiLattice Word Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

top :: Word Source #

JoinSemiLattice Word Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(\/) :: Word -> Word -> Word Source #

MeetSemiLattice Word Source # 
Instance details

Defined in NumHask.Algebra.Lattice

Methods

(/\) :: Word -> Word -> Word Source #

Basis Word Source # 
Instance details

Defined in NumHask.Algebra.Metric

Associated Types

type Mag Word Source #

type Base Word Source #

Epsilon Word Source # 
Instance details

Defined in NumHask.Algebra.Metric

Methods

epsilon :: Word Source #

Multiplicative Word Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

(*) :: Word -> Word -> Word Source #

one :: Word Source #

InvolutiveRing Word Source # 
Instance details

Defined in NumHask.Algebra.Ring

Methods

adj :: Word -> Word Source #

FromInteger Word Source # 
Instance details

Defined in NumHask.Data.Integral

Integral Word Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

div :: Word -> Word -> Word Source #

mod :: Word -> Word -> Word Source #

divMod :: Word -> Word -> (Word, Word) Source #

quot :: Word -> Word -> Word Source #

rem :: Word -> Word -> Word Source #

quotRem :: Word -> Word -> (Word, Word) Source #

FromIntegral Word Integer Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word Int Source # 
Instance details

Defined in NumHask.Data.Integral

FromIntegral Word Word Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word Integer Source # 
Instance details

Defined in NumHask.Data.Integral

ToIntegral Word Int Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Word -> Int Source #

ToIntegral Word Word Source # 
Instance details

Defined in NumHask.Data.Integral

Methods

toIntegral :: Word -> Word Source #

ToRatio Word Integer Source # 
Instance details

Defined in NumHask.Data.Rational

Generic1 (URec Word :: k -> Type) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep1 (URec Word) :: k -> Type #

Methods

from1 :: forall (a :: k0). URec Word a -> Rep1 (URec Word) a #

to1 :: forall (a :: k0). Rep1 (URec Word) a -> URec Word a #

Foldable (UWord :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UWord m -> m #

foldMap :: Monoid m => (a -> m) -> UWord a -> m #

foldMap' :: Monoid m => (a -> m) -> UWord a -> m #

foldr :: (a -> b -> b) -> b -> UWord a -> b #

foldr' :: (a -> b -> b) -> b -> UWord a -> b #

foldl :: (b -> a -> b) -> b -> UWord a -> b #

foldl' :: (b -> a -> b) -> b -> UWord a -> b #

foldr1 :: (a -> a -> a) -> UWord a -> a #

foldl1 :: (a -> a -> a) -> UWord a -> a #

toList :: UWord a -> [a] #

null :: UWord a -> Bool #

length :: UWord a -> Int #

elem :: Eq a => a -> UWord a -> Bool #

maximum :: Ord a => UWord a -> a #

minimum :: Ord a => UWord a -> a #

sum :: Num a => UWord a -> a #

product :: Num a => UWord a -> a #

Traversable (UWord :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UWord a -> f (UWord b) #

sequenceA :: Applicative f => UWord (f a) -> f (UWord a) #

mapM :: Monad m => (a -> m b) -> UWord a -> m (UWord b) #

sequence :: Monad m => UWord (m a) -> m (UWord a) #

Functor (URec Word :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Word a -> URec Word b #

(<$) :: a -> URec Word b -> URec Word a #

Generic (URec Word p) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep (URec Word p) :: Type -> Type #

Methods

from :: URec Word p -> Rep (URec Word p) x #

to :: Rep (URec Word p) x -> URec Word p #

Show (URec Word p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

showsPrec :: Int -> URec Word p -> ShowS #

show :: URec Word p -> String #

showList :: [URec Word p] -> ShowS #

Eq (URec Word p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Word p -> URec Word p -> Bool #

(/=) :: URec Word p -> URec Word p -> Bool #

Ord (URec Word p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

compare :: URec Word p -> URec Word p -> Ordering #

(<) :: URec Word p -> URec Word p -> Bool #

(<=) :: URec Word p -> URec Word p -> Bool #

(>) :: URec Word p -> URec Word p -> Bool #

(>=) :: URec Word p -> URec Word p -> Bool #

max :: URec Word p -> URec Word p -> URec Word p #

min :: URec Word p -> URec Word p -> URec Word p #

type Base Word Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Base Word = Word
type Mag Word Source # 
Instance details

Defined in NumHask.Algebra.Metric

type Mag Word = Word
data URec Word (p :: k)

Used for marking occurrences of Word#

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

data URec Word (p :: k) = UWord {}
type Rep1 (URec Word :: k -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep1 (URec Word :: k -> Type) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UWord" 'PrefixI 'True) (S1 ('MetaSel ('Just "uWord#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UWord :: k -> Type)))
type Rep (URec Word p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

type Rep (URec Word p) = D1 ('MetaData "URec" "GHC.Generics" "base" 'False) (C1 ('MetaCons "UWord" 'PrefixI 'True) (S1 ('MetaSel ('Just "uWord#") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (UWord :: Type -> Type)))

data Maybe a #

The Maybe type encapsulates an optional value. A value of type Maybe a either contains a value of type a (represented as Just a), or it is empty (represented as Nothing). Using Maybe is a good way to deal with errors or exceptional cases without resorting to drastic measures such as error.

The Maybe type is also a monad. It is a simple kind of error monad, where all errors are represented by Nothing. A richer error monad can be built using the Either type.

Constructors

Nothing 
Just a 

Instances

Instances details
MonadFail Maybe

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fail

Methods

fail :: String -> Maybe a #

Foldable Maybe

Since: base-2.1

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Maybe m -> m #

foldMap :: Monoid m => (a -> m) -> Maybe a -> m #

foldMap' :: Monoid m => (a -> m) -> Maybe a -> m #

foldr :: (a -> b -> b) -> b -> Maybe a -> b #

foldr' :: (a -> b -> b) -> b -> Maybe a -> b #

foldl :: (b -> a -> b) -> b -> Maybe a -> b #

foldl' :: (b -> a -> b) -> b -> Maybe a -> b #

foldr1 :: (a -> a -> a) -> Maybe a -> a #

foldl1 :: (a -> a -> a) -> Maybe a -> a #

toList :: Maybe a -> [a] #

null :: Maybe a -> Bool #

length :: Maybe a -> Int #

elem :: Eq a => a -> Maybe a -> Bool #

maximum :: Ord a => Maybe a -> a #

minimum :: Ord a => Maybe a -> a #

sum :: Num a => Maybe a -> a #

product :: Num a => Maybe a -> a #

Traversable Maybe

Since: base-2.1

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Maybe a -> f (Maybe b) #

sequenceA :: Applicative f => Maybe (f a) -> f (Maybe a) #

mapM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) #

sequence :: Monad m => Maybe (m a) -> m (Maybe a) #

Alternative Maybe

Picks the leftmost Just value, or, alternatively, Nothing.

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

empty :: Maybe a #

(<|>) :: Maybe a -> Maybe a -> Maybe a #

some :: Maybe a -> Maybe [a] #

many :: Maybe a -> Maybe [a] #

Applicative Maybe

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> Maybe a #

(<*>) :: Maybe (a -> b) -> Maybe a -> Maybe b #

liftA2 :: (a -> b -> c) -> Maybe a -> Maybe b -> Maybe c #

(*>) :: Maybe a -> Maybe b -> Maybe b #

(<*) :: Maybe a -> Maybe b -> Maybe a #

Functor Maybe

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> Maybe a -> Maybe b #

(<$) :: a -> Maybe b -> Maybe a #

Monad Maybe

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

(>>=) :: Maybe a -> (a -> Maybe b) -> Maybe b #

(>>) :: Maybe a -> Maybe b -> Maybe b #

return :: a -> Maybe a #

MonadPlus Maybe

Picks the leftmost Just value, or, alternatively, Nothing.

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mzero :: Maybe a #

mplus :: Maybe a -> Maybe a -> Maybe a #

Generic1 Maybe 
Instance details

Defined in GHC.Generics

Associated Types

type Rep1 Maybe :: k -> Type #

Methods

from1 :: forall (a :: k). Maybe a -> Rep1 Maybe a #

to1 :: forall (a :: k). Rep1 Maybe a -> Maybe a #

Data a => Data (Maybe a)

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Maybe a -> c (Maybe a) #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Maybe a) #

toConstr :: Maybe a -> Constr #

dataTypeOf :: Maybe a -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Maybe a)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a)) #

gmapT :: (forall b. Data b => b -> b) -> Maybe a -> Maybe a #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Maybe a -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Maybe a -> r #

gmapQ :: (forall d. Data d => d -> u) -> Maybe a -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Maybe a -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) #

Semigroup a => Monoid (Maybe a)

Lift a semigroup into Maybe forming a Monoid according to http://en.wikipedia.org/wiki/Monoid: "Any semigroup S may be turned into a monoid simply by adjoining an element e not in S and defining e*e = e and e*s = s = s*e for all s ∈ S."

Since 4.11.0: constraint on inner a value generalised from Monoid to Semigroup.

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: Maybe a #

mappend :: Maybe a -> Maybe a -> Maybe a #

mconcat :: [Maybe a] -> Maybe a #

Semigroup a => Semigroup (Maybe a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: Maybe a -> Maybe a -> Maybe a #

sconcat :: NonEmpty (Maybe a) -> Maybe a #

stimes :: Integral b => b -> Maybe a -> Maybe a #

Generic (Maybe a) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep (Maybe a) :: Type -> Type #

Methods

from :: Maybe a -> Rep (Maybe a) x #

to :: Rep (Maybe a) x -> Maybe a #

SingKind a => SingKind (Maybe a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Associated Types

type DemoteRep (Maybe a)

Methods

fromSing :: forall (a0 :: Maybe a). Sing a0 -> DemoteRep (Maybe a)

Read a => Read (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Read

Show a => Show (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Maybe a -> ShowS #

show :: Maybe a -> String #

showList :: [Maybe a] -> ShowS #

Eq a => Eq (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Maybe

Methods

(==) :: Maybe a -> Maybe a -> Bool #

(/=) :: Maybe a -> Maybe a -> Bool #

Ord a => Ord (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Maybe

Methods

compare :: Maybe a -> Maybe a -> Ordering #

(<) :: Maybe a -> Maybe a -> Bool #

(<=) :: Maybe a -> Maybe a -> Bool #

(>) :: Maybe a -> Maybe a -> Bool #

(>=) :: Maybe a -> Maybe a -> Bool #

max :: Maybe a -> Maybe a -> Maybe a #

min :: Maybe a -> Maybe a -> Maybe a #

SingI ('Nothing :: Maybe a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

sing :: Sing 'Nothing

SingI a2 => SingI ('Just a2 :: Maybe a1)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

sing :: Sing ('Just a2)

type Rep1 Maybe

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

type Rep1 Maybe = D1 ('MetaData "Maybe" "GHC.Maybe" "base" 'False) (C1 ('MetaCons "Nothing" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Just" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))
type DemoteRep (Maybe a) 
Instance details

Defined in GHC.Generics

type DemoteRep (Maybe a) = Maybe (DemoteRep a)
type Rep (Maybe a)

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

type Rep (Maybe a) = D1 ('MetaData "Maybe" "GHC.Maybe" "base" 'False) (C1 ('MetaCons "Nothing" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Just" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))
data Sing (b :: Maybe a) 
Instance details

Defined in GHC.Generics

data Sing (b :: Maybe a) where

class a ~# b => (a :: k) ~ (b :: k) infix 4 #

Lifted, homogeneous equality. By lifted, we mean that it can be bogus (deferred type error). By homogeneous, the two types a and b must have the same kinds.

class Num a => Fractional a #

Fractional numbers, supporting real division.

The Haskell Report defines no laws for Fractional. However, (+) and (*) are customarily expected to define a division ring and have the following properties:

recip gives the multiplicative inverse
x * recip x = recip x * x = fromInteger 1
Totality of toRational
toRational is total
Coherence with toRational
if the type also implements Real, then fromRational is a left inverse for toRational, i.e. fromRational (toRational i) = i

Note that it isn't customarily expected that a type instance of Fractional implement a field. However, all instances in base do.

Minimal complete definition

fromRational, (recip | (/))

Instances

Instances details
Fractional a => Fractional (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Fractional a => Fractional (Down a)

Since: base-4.14.0.0

Instance details

Defined in Data.Ord

Methods

(/) :: Down a -> Down a -> Down a #

recip :: Down a -> Down a #

fromRational :: Rational -> Down a #

Integral a => Fractional (Ratio a)

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

(/) :: Ratio a -> Ratio a -> Ratio a #

recip :: Ratio a -> Ratio a #

fromRational :: Rational -> Ratio a #

Fractional a => Fractional (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

(/) :: Const a b -> Const a b -> Const a b #

recip :: Const a b -> Const a b #

fromRational :: Rational -> Const a b #

class (Num a, Ord a) => Real a #

Real numbers.

The Haskell report defines no laws for Real, however Real instances are customarily expected to adhere to the following law:

Coherence with fromRational
if the type also implements Fractional, then fromRational is a left inverse for toRational, i.e. fromRational (toRational i) = i

Minimal complete definition

toRational

Instances

Instances details
Real Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

toRational :: Int16 -> Rational #

Real Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

toRational :: Int32 -> Rational #

Real Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

toRational :: Int64 -> Rational #

Real Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

toRational :: Int8 -> Rational #

Real Word16

Since: base-2.1

Instance details

Defined in GHC.Word

Real Word32

Since: base-2.1

Instance details

Defined in GHC.Word

Real Word64

Since: base-2.1

Instance details

Defined in GHC.Word

Real Word8

Since: base-2.1

Instance details

Defined in GHC.Word

Methods

toRational :: Word8 -> Rational #

Real Integer

Since: base-2.0.1

Instance details

Defined in GHC.Real

Real Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Real

Real Int

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

toRational :: Int -> Rational #

Real Word

Since: base-2.1

Instance details

Defined in GHC.Real

Methods

toRational :: Word -> Rational #

Real a => Real (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Methods

toRational :: Identity a -> Rational #

Real a => Real (Down a)

Since: base-4.14.0.0

Instance details

Defined in Data.Ord

Methods

toRational :: Down a -> Rational #

Integral a => Real (Ratio a)

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

toRational :: Ratio a -> Rational #

Real a => Real (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

toRational :: Const a b -> Rational #

class Eq a where #

The Eq class defines equality (==) and inequality (/=). All the basic datatypes exported by the Prelude are instances of Eq, and Eq may be derived for any datatype whose constituents are also instances of Eq.

The Haskell Report defines no laws for Eq. However, instances are encouraged to follow these properties:

Reflexivity
x == x = True
Symmetry
x == y = y == x
Transitivity
if x == y && y == z = True, then x == z = True
Extensionality
if x == y = True and f is a function whose return type is an instance of Eq, then f x == f y = True
Negation
x /= y = not (x == y)

Minimal complete definition: either == or /=.

Minimal complete definition

(==) | (/=)

Methods

(==) :: a -> a -> Bool infix 4 #

(/=) :: a -> a -> Bool infix 4 #

Instances

Instances details
Eq Constr

Equality of constructors

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

(==) :: Constr -> Constr -> Bool #

(/=) :: Constr -> Constr -> Bool #

Eq ConstrRep

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Eq DataRep

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

(==) :: DataRep -> DataRep -> Bool #

(/=) :: DataRep -> DataRep -> Bool #

Eq Fixity

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

(==) :: Fixity -> Fixity -> Bool #

(/=) :: Fixity -> Fixity -> Bool #

Eq All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: All -> All -> Bool #

(/=) :: All -> All -> Bool #

Eq Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: Any -> Any -> Bool #

(/=) :: Any -> Any -> Bool #

Eq SomeTypeRep 
Instance details

Defined in Data.Typeable.Internal

Eq Version

Since: base-2.1

Instance details

Defined in Data.Version

Methods

(==) :: Version -> Version -> Bool #

(/=) :: Version -> Version -> Bool #

Eq Void

Since: base-4.8.0.0

Instance details

Defined in GHC.Base

Methods

(==) :: Void -> Void -> Bool #

(/=) :: Void -> Void -> Bool #

Eq ErrorCall

Since: base-4.7.0.0

Instance details

Defined in GHC.Exception

Eq ArithException

Since: base-3.0

Instance details

Defined in GHC.Exception.Type

Eq SpecConstrAnnotation

Since: base-4.3.0.0

Instance details

Defined in GHC.Exts

Eq Associativity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Eq DecidedStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Eq Fixity

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: Fixity -> Fixity -> Bool #

(/=) :: Fixity -> Fixity -> Bool #

Eq SourceStrictness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Eq SourceUnpackedness

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Eq MaskingState

Since: base-4.3.0.0

Instance details

Defined in GHC.IO

Eq ArrayException

Since: base-4.2.0.0

Instance details

Defined in GHC.IO.Exception

Eq AsyncException

Since: base-4.2.0.0

Instance details

Defined in GHC.IO.Exception

Eq ExitCode 
Instance details

Defined in GHC.IO.Exception

Eq IOErrorType

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Eq IOException

Since: base-4.1.0.0

Instance details

Defined in GHC.IO.Exception

Eq Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

(==) :: Int16 -> Int16 -> Bool #

(/=) :: Int16 -> Int16 -> Bool #

Eq Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

(==) :: Int32 -> Int32 -> Bool #

(/=) :: Int32 -> Int32 -> Bool #

Eq Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

(==) :: Int64 -> Int64 -> Bool #

(/=) :: Int64 -> Int64 -> Bool #

Eq Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

(==) :: Int8 -> Int8 -> Bool #

(/=) :: Int8 -> Int8 -> Bool #

Eq IoSubSystem 
Instance details

Defined in GHC.RTS.Flags

Eq SrcLoc

Since: base-4.9.0.0

Instance details

Defined in GHC.Stack.Types

Methods

(==) :: SrcLoc -> SrcLoc -> Bool #

(/=) :: SrcLoc -> SrcLoc -> Bool #

Eq Word16

Since: base-2.1

Instance details

Defined in GHC.Word

Methods

(==) :: Word16 -> Word16 -> Bool #

(/=) :: Word16 -> Word16 -> Bool #

Eq Word32

Since: base-2.1

Instance details

Defined in GHC.Word

Methods

(==) :: Word32 -> Word32 -> Bool #

(/=) :: Word32 -> Word32 -> Bool #

Eq Word64

Since: base-2.1

Instance details

Defined in GHC.Word

Methods

(==) :: Word64 -> Word64 -> Bool #

(/=) :: Word64 -> Word64 -> Bool #

Eq Word8

Since: base-2.1

Instance details

Defined in GHC.Word

Methods

(==) :: Word8 -> Word8 -> Bool #

(/=) :: Word8 -> Word8 -> Bool #

Eq Lexeme

Since: base-2.1

Instance details

Defined in Text.Read.Lex

Methods

(==) :: Lexeme -> Lexeme -> Bool #

(/=) :: Lexeme -> Lexeme -> Bool #

Eq Number

Since: base-4.6.0.0

Instance details

Defined in Text.Read.Lex

Methods

(==) :: Number -> Number -> Bool #

(/=) :: Number -> Number -> Bool #

Eq BigNat 
Instance details

Defined in GHC.Num.BigNat

Methods

(==) :: BigNat -> BigNat -> Bool #

(/=) :: BigNat -> BigNat -> Bool #

Eq Module 
Instance details

Defined in GHC.Classes

Methods

(==) :: Module -> Module -> Bool #

(/=) :: Module -> Module -> Bool #

Eq Ordering 
Instance details

Defined in GHC.Classes

Eq TrName 
Instance details

Defined in GHC.Classes

Methods

(==) :: TrName -> TrName -> Bool #

(/=) :: TrName -> TrName -> Bool #

Eq TyCon 
Instance details

Defined in GHC.Classes

Methods

(==) :: TyCon -> TyCon -> Bool #

(/=) :: TyCon -> TyCon -> Bool #

Eq Integer 
Instance details

Defined in GHC.Num.Integer

Methods

(==) :: Integer -> Integer -> Bool #

(/=) :: Integer -> Integer -> Bool #

Eq Natural 
Instance details

Defined in GHC.Num.Natural

Methods

(==) :: Natural -> Natural -> Bool #

(/=) :: Natural -> Natural -> Bool #

Eq () 
Instance details

Defined in GHC.Classes

Methods

(==) :: () -> () -> Bool #

(/=) :: () -> () -> Bool #

Eq Bool 
Instance details

Defined in GHC.Classes

Methods

(==) :: Bool -> Bool -> Bool #

(/=) :: Bool -> Bool -> Bool #

Eq Char 
Instance details

Defined in GHC.Classes

Methods

(==) :: Char -> Char -> Bool #

(/=) :: Char -> Char -> Bool #

Eq Double

Note that due to the presence of NaN, Double's Eq instance does not satisfy reflexivity.

>>> 0/0 == (0/0 :: Double)
False

Also note that Double's Eq instance does not satisfy substitutivity:

>>> 0 == (-0 :: Double)
True
>>> recip 0 == recip (-0 :: Double)
False
Instance details

Defined in GHC.Classes

Methods

(==) :: Double -> Double -> Bool #

(/=) :: Double -> Double -> Bool #

Eq Float

Note that due to the presence of NaN, Float's Eq instance does not satisfy reflexivity.

>>> 0/0 == (0/0 :: Float)
False

Also note that Float's Eq instance does not satisfy extensionality:

>>> 0 == (-0 :: Float)
True
>>> recip 0 == recip (-0 :: Float)
False
Instance details

Defined in GHC.Classes

Methods

(==) :: Float -> Float -> Bool #

(/=) :: Float -> Float -> Bool #

Eq Int 
Instance details

Defined in GHC.Classes

Methods

(==) :: Int -> Int -> Bool #

(/=) :: Int -> Int -> Bool #

Eq Word 
Instance details

Defined in GHC.Classes

Methods

(==) :: Word -> Word -> Bool #

(/=) :: Word -> Word -> Bool #

Eq a => Eq (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in Control.Applicative

Methods

(==) :: ZipList a -> ZipList a -> Bool #

(/=) :: ZipList a -> ZipList a -> Bool #

Eq a => Eq (Identity a)

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

(==) :: Identity a -> Identity a -> Bool #

(/=) :: Identity a -> Identity a -> Bool #

Eq a => Eq (First a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

(==) :: First a -> First a -> Bool #

(/=) :: First a -> First a -> Bool #

Eq a => Eq (Last a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

(==) :: Last a -> Last a -> Bool #

(/=) :: Last a -> Last a -> Bool #

Eq a => Eq (Down a)

Since: base-4.6.0.0

Instance details

Defined in Data.Ord

Methods

(==) :: Down a -> Down a -> Bool #

(/=) :: Down a -> Down a -> Bool #

Eq a => Eq (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: First a -> First a -> Bool #

(/=) :: First a -> First a -> Bool #

Eq a => Eq (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: Last a -> Last a -> Bool #

(/=) :: Last a -> Last a -> Bool #

Eq a => Eq (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: Max a -> Max a -> Bool #

(/=) :: Max a -> Max a -> Bool #

Eq a => Eq (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: Min a -> Min a -> Bool #

(/=) :: Min a -> Min a -> Bool #

Eq m => Eq (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Eq a => Eq (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: Dual a -> Dual a -> Bool #

(/=) :: Dual a -> Dual a -> Bool #

Eq a => Eq (Product a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: Product a -> Product a -> Bool #

(/=) :: Product a -> Product a -> Bool #

Eq a => Eq (Sum a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: Sum a -> Sum a -> Bool #

(/=) :: Sum a -> Sum a -> Bool #

Eq a => Eq (NonEmpty a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(==) :: NonEmpty a -> NonEmpty a -> Bool #

(/=) :: NonEmpty a -> NonEmpty a -> Bool #

Eq p => Eq (Par1 p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: Par1 p -> Par1 p -> Bool #

(/=) :: Par1 p -> Par1 p -> Bool #

Eq (FunPtr a) 
Instance details

Defined in GHC.Ptr

Methods

(==) :: FunPtr a -> FunPtr a -> Bool #

(/=) :: FunPtr a -> FunPtr a -> Bool #

Eq (Ptr a)

Since: base-2.1

Instance details

Defined in GHC.Ptr

Methods

(==) :: Ptr a -> Ptr a -> Bool #

(/=) :: Ptr a -> Ptr a -> Bool #

Eq a => Eq (Ratio a)

Since: base-2.1

Instance details

Defined in GHC.Real

Methods

(==) :: Ratio a -> Ratio a -> Bool #

(/=) :: Ratio a -> Ratio a -> Bool #

Eq a => Eq (Sum a) Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

(==) :: Sum a -> Sum a -> Bool #

(/=) :: Sum a -> Sum a -> Bool #

Eq a => Eq (EuclideanPair a) Source # 
Instance details

Defined in NumHask.Algebra.Metric

Eq a => Eq (Polar a) Source # 
Instance details

Defined in NumHask.Algebra.Metric

Methods

(==) :: Polar a -> Polar a -> Bool #

(/=) :: Polar a -> Polar a -> Bool #

Eq a => Eq (Product a) Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

(==) :: Product a -> Product a -> Bool #

(/=) :: Product a -> Product a -> Bool #

Eq a => Eq (Complex a) Source # 
Instance details

Defined in NumHask.Data.Complex

Methods

(==) :: Complex a -> Complex a -> Bool #

(/=) :: Complex a -> Complex a -> Bool #

Eq a => Eq (Positive a) Source # 
Instance details

Defined in NumHask.Data.Positive

Methods

(==) :: Positive a -> Positive a -> Bool #

(/=) :: Positive a -> Positive a -> Bool #

(Eq a, Subtractive a, EndoBased a, Absolute a, Integral a) => Eq (Ratio a) Source # 
Instance details

Defined in NumHask.Data.Rational

Methods

(==) :: Ratio a -> Ratio a -> Bool #

(/=) :: Ratio a -> Ratio a -> Bool #

Eq a => Eq (Wrapped a) Source # 
Instance details

Defined in NumHask.Data.Wrapped

Methods

(==) :: Wrapped a -> Wrapped a -> Bool #

(/=) :: Wrapped a -> Wrapped a -> Bool #

Eq a => Eq (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Maybe

Methods

(==) :: Maybe a -> Maybe a -> Bool #

(/=) :: Maybe a -> Maybe a -> Bool #

Eq a => Eq (a) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a) -> (a) -> Bool #

(/=) :: (a) -> (a) -> Bool #

Eq a => Eq [a] 
Instance details

Defined in GHC.Classes

Methods

(==) :: [a] -> [a] -> Bool #

(/=) :: [a] -> [a] -> Bool #

(Eq a, Eq b) => Eq (Either a b)

Since: base-2.1

Instance details

Defined in Data.Either

Methods

(==) :: Either a b -> Either a b -> Bool #

(/=) :: Either a b -> Either a b -> Bool #

Eq a => Eq (Arg a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(==) :: Arg a b -> Arg a b -> Bool #

(/=) :: Arg a b -> Arg a b -> Bool #

Eq (TypeRep a)

Since: base-2.1

Instance details

Defined in Data.Typeable.Internal

Methods

(==) :: TypeRep a -> TypeRep a -> Bool #

(/=) :: TypeRep a -> TypeRep a -> Bool #

Eq (U1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: U1 p -> U1 p -> Bool #

(/=) :: U1 p -> U1 p -> Bool #

Eq (V1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: V1 p -> V1 p -> Bool #

(/=) :: V1 p -> V1 p -> Bool #

(Eq a, Eq b) => Eq (a, b) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b) -> (a, b) -> Bool #

(/=) :: (a, b) -> (a, b) -> Bool #

Eq a => Eq (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

(==) :: Const a b -> Const a b -> Bool #

(/=) :: Const a b -> Const a b -> Bool #

Eq (f a) => Eq (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

(==) :: Ap f a -> Ap f a -> Bool #

(/=) :: Ap f a -> Ap f a -> Bool #

Eq (f a) => Eq (Alt f a)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(==) :: Alt f a -> Alt f a -> Bool #

(/=) :: Alt f a -> Alt f a -> Bool #

Eq (OrderingI a b) 
Instance details

Defined in Data.Type.Ord

Methods

(==) :: OrderingI a b -> OrderingI a b -> Bool #

(/=) :: OrderingI a b -> OrderingI a b -> Bool #

(Generic1 f, Eq (Rep1 f a)) => Eq (Generically1 f a)

Since: base-4.18.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: Generically1 f a -> Generically1 f a -> Bool #

(/=) :: Generically1 f a -> Generically1 f a -> Bool #

Eq (f p) => Eq (Rec1 f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: Rec1 f p -> Rec1 f p -> Bool #

(/=) :: Rec1 f p -> Rec1 f p -> Bool #

Eq (URec (Ptr ()) p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool #

(/=) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool #

Eq (URec Char p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Char p -> URec Char p -> Bool #

(/=) :: URec Char p -> URec Char p -> Bool #

Eq (URec Double p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Double p -> URec Double p -> Bool #

(/=) :: URec Double p -> URec Double p -> Bool #

Eq (URec Float p) 
Instance details

Defined in GHC.Generics

Methods

(==) :: URec Float p -> URec Float p -> Bool #

(/=) :: URec Float p -> URec Float p -> Bool #

Eq (URec Int p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Int p -> URec Int p -> Bool #

(/=) :: URec Int p -> URec Int p -> Bool #

Eq (URec Word p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: URec Word p -> URec Word p -> Bool #

(/=) :: URec Word p -> URec Word p -> Bool #

(Eq a, Eq b, Eq c) => Eq (a, b, c) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c) -> (a, b, c) -> Bool #

(/=) :: (a, b, c) -> (a, b, c) -> Bool #

(Eq (f p), Eq (g p)) => Eq ((f :*: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: (f :*: g) p -> (f :*: g) p -> Bool #

(/=) :: (f :*: g) p -> (f :*: g) p -> Bool #

(Eq (f p), Eq (g p)) => Eq ((f :+: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: (f :+: g) p -> (f :+: g) p -> Bool #

(/=) :: (f :+: g) p -> (f :+: g) p -> Bool #

Eq c => Eq (K1 i c p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: K1 i c p -> K1 i c p -> Bool #

(/=) :: K1 i c p -> K1 i c p -> Bool #

(Eq a, Eq b, Eq c, Eq d) => Eq (a, b, c, d) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d) -> (a, b, c, d) -> Bool #

(/=) :: (a, b, c, d) -> (a, b, c, d) -> Bool #

Eq (f (g p)) => Eq ((f :.: g) p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: (f :.: g) p -> (f :.: g) p -> Bool #

(/=) :: (f :.: g) p -> (f :.: g) p -> Bool #

Eq (f p) => Eq (M1 i c f p)

Since: base-4.7.0.0

Instance details

Defined in GHC.Generics

Methods

(==) :: M1 i c f p -> M1 i c f p -> Bool #

(/=) :: M1 i c f p -> M1 i c f p -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e) => Eq (a, b, c, d, e) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e) -> (a, b, c, d, e) -> Bool #

(/=) :: (a, b, c, d, e) -> (a, b, c, d, e) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f) => Eq (a, b, c, d, e, f) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> Bool #

(/=) :: (a, b, c, d, e, f) -> (a, b, c, d, e, f) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g) => Eq (a, b, c, d, e, f, g) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> Bool #

(/=) :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h) => Eq (a, b, c, d, e, f, g, h) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h, Eq i) => Eq (a, b, c, d, e, f, g, h, i) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h, Eq i, Eq j) => Eq (a, b, c, d, e, f, g, h, i, j) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h, Eq i, Eq j, Eq k) => Eq (a, b, c, d, e, f, g, h, i, j, k) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h, i, j, k) -> (a, b, c, d, e, f, g, h, i, j, k) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h, Eq i, Eq j, Eq k, Eq l) => Eq (a, b, c, d, e, f, g, h, i, j, k, l) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h, i, j, k, l) -> (a, b, c, d, e, f, g, h, i, j, k, l) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h, Eq i, Eq j, Eq k, Eq l, Eq m) => Eq (a, b, c, d, e, f, g, h, i, j, k, l, m) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h, Eq i, Eq j, Eq k, Eq l, Eq m, Eq n) => Eq (a, b, c, d, e, f, g, h, i, j, k, l, m, n) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Bool #

(Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h, Eq i, Eq j, Eq k, Eq l, Eq m, Eq n, Eq o) => Eq (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) 
Instance details

Defined in GHC.Classes

Methods

(==) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Bool #

(/=) :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Bool #

class Semigroup a => Monoid a where #

The class of monoids (types with an associative binary operation that has an identity). Instances should satisfy the following:

Right identity
x <> mempty = x
Left identity
mempty <> x = x
Associativity
x <> (y <> z) = (x <> y) <> z (Semigroup law)
Concatenation
mconcat = foldr (<>) mempty

You can alternatively define mconcat instead of mempty, in which case the laws are:

Unit
mconcat (pure x) = x
Multiplication
mconcat (join xss) = mconcat (fmap mconcat xss)
Subclass
mconcat (toList xs) = sconcat xs

The method names refer to the monoid of lists under concatenation, but there are many other instances.

Some types can be viewed as a monoid in more than one way, e.g. both addition and multiplication on numbers. In such cases we often define newtypes and make those instances of Monoid, e.g. Sum and Product.

NOTE: Semigroup is a superclass of Monoid since base-4.11.0.0.

Minimal complete definition

mempty | mconcat

Methods

mempty :: a #

Identity of mappend

>>> "Hello world" <> mempty
"Hello world"

mappend :: a -> a -> a #

An associative operation

NOTE: This method is redundant and has the default implementation mappend = (<>) since base-4.11.0.0. Should it be implemented manually, since mappend is a synonym for (<>), it is expected that the two functions are defined the same way. In a future GHC release mappend will be removed from Monoid.

mconcat :: [a] -> a #

Fold a list using the monoid.

For most types, the default definition for mconcat will be used, but the function is included in the class definition so that an optimized version can be provided for specific types.

>>> mconcat ["Hello", " ", "Haskell", "!"]
"Hello Haskell!"

Instances

Instances details
Monoid All

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: All #

mappend :: All -> All -> All #

mconcat :: [All] -> All #

Monoid Any

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Any #

mappend :: Any -> Any -> Any #

mconcat :: [Any] -> Any #

Monoid Ordering

Since: base-2.1

Instance details

Defined in GHC.Base

Monoid ()

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: () #

mappend :: () -> () -> () #

mconcat :: [()] -> () #

Monoid a => Monoid (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Methods

mempty :: Identity a #

mappend :: Identity a -> Identity a -> Identity a #

mconcat :: [Identity a] -> Identity a #

Monoid (First a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

mempty :: First a #

mappend :: First a -> First a -> First a #

mconcat :: [First a] -> First a #

Monoid (Last a)

Since: base-2.1

Instance details

Defined in Data.Monoid

Methods

mempty :: Last a #

mappend :: Last a -> Last a -> Last a #

mconcat :: [Last a] -> Last a #

Monoid a => Monoid (Down a)

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

mempty :: Down a #

mappend :: Down a -> Down a -> Down a #

mconcat :: [Down a] -> Down a #

(Ord a, Bounded a) => Monoid (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mempty :: Max a #

mappend :: Max a -> Max a -> Max a #

mconcat :: [Max a] -> Max a #

(Ord a, Bounded a) => Monoid (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mempty :: Min a #

mappend :: Min a -> Min a -> Min a #

mconcat :: [Min a] -> Min a #

Monoid m => Monoid (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Monoid a => Monoid (Dual a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Dual a #

mappend :: Dual a -> Dual a -> Dual a #

mconcat :: [Dual a] -> Dual a #

Monoid (Endo a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Endo a #

mappend :: Endo a -> Endo a -> Endo a #

mconcat :: [Endo a] -> Endo a #

Num a => Monoid (Product a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Product a #

mappend :: Product a -> Product a -> Product a #

mconcat :: [Product a] -> Product a #

Num a => Monoid (Sum a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Sum a #

mappend :: Sum a -> Sum a -> Sum a #

mconcat :: [Sum a] -> Sum a #

(Generic a, Monoid (Rep a ())) => Monoid (Generically a)

Since: base-4.17.0.0

Instance details

Defined in GHC.Generics

Monoid p => Monoid (Par1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

mempty :: Par1 p #

mappend :: Par1 p -> Par1 p -> Par1 p #

mconcat :: [Par1 p] -> Par1 p #

Monoid a => Monoid (IO a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

mempty :: IO a #

mappend :: IO a -> IO a -> IO a #

mconcat :: [IO a] -> IO a #

Additive a => Monoid (Sum a) Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

mempty :: Sum a #

mappend :: Sum a -> Sum a -> Sum a #

mconcat :: [Sum a] -> Sum a #

Multiplicative a => Monoid (Product a) Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

mempty :: Product a #

mappend :: Product a -> Product a -> Product a #

mconcat :: [Product a] -> Product a #

Semigroup a => Monoid (Maybe a)

Lift a semigroup into Maybe forming a Monoid according to http://en.wikipedia.org/wiki/Monoid: "Any semigroup S may be turned into a monoid simply by adjoining an element e not in S and defining e*e = e and e*s = s = s*e for all s ∈ S."

Since 4.11.0: constraint on inner a value generalised from Monoid to Semigroup.

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: Maybe a #

mappend :: Maybe a -> Maybe a -> Maybe a #

mconcat :: [Maybe a] -> Maybe a #

Monoid a => Monoid (a)

Since: base-4.15

Instance details

Defined in GHC.Base

Methods

mempty :: (a) #

mappend :: (a) -> (a) -> (a) #

mconcat :: [(a)] -> (a) #

Monoid [a]

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: [a] #

mappend :: [a] -> [a] -> [a] #

mconcat :: [[a]] -> [a] #

Monoid (U1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

mempty :: U1 p #

mappend :: U1 p -> U1 p -> U1 p #

mconcat :: [U1 p] -> U1 p #

(Monoid a, Monoid b) => Monoid (a, b)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: (a, b) #

mappend :: (a, b) -> (a, b) -> (a, b) #

mconcat :: [(a, b)] -> (a, b) #

Monoid b => Monoid (a -> b)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: a -> b #

mappend :: (a -> b) -> (a -> b) -> a -> b #

mconcat :: [a -> b] -> a -> b #

Monoid a => Monoid (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

mempty :: Const a b #

mappend :: Const a b -> Const a b -> Const a b #

mconcat :: [Const a b] -> Const a b #

(Applicative f, Monoid a) => Monoid (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

mempty :: Ap f a #

mappend :: Ap f a -> Ap f a -> Ap f a #

mconcat :: [Ap f a] -> Ap f a #

Alternative f => Monoid (Alt f a)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Alt f a #

mappend :: Alt f a -> Alt f a -> Alt f a #

mconcat :: [Alt f a] -> Alt f a #

Monoid (f p) => Monoid (Rec1 f p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

mempty :: Rec1 f p #

mappend :: Rec1 f p -> Rec1 f p -> Rec1 f p #

mconcat :: [Rec1 f p] -> Rec1 f p #

(Monoid a, Monoid b, Monoid c) => Monoid (a, b, c)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: (a, b, c) #

mappend :: (a, b, c) -> (a, b, c) -> (a, b, c) #

mconcat :: [(a, b, c)] -> (a, b, c) #

(Monoid (f p), Monoid (g p)) => Monoid ((f :*: g) p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

mempty :: (f :*: g) p #

mappend :: (f :*: g) p -> (f :*: g) p -> (f :*: g) p #

mconcat :: [(f :*: g) p] -> (f :*: g) p #

Monoid c => Monoid (K1 i c p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

mempty :: K1 i c p #

mappend :: K1 i c p -> K1 i c p -> K1 i c p #

mconcat :: [K1 i c p] -> K1 i c p #

(Monoid a, Monoid b, Monoid c, Monoid d) => Monoid (a, b, c, d)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: (a, b, c, d) #

mappend :: (a, b, c, d) -> (a, b, c, d) -> (a, b, c, d) #

mconcat :: [(a, b, c, d)] -> (a, b, c, d) #

Monoid (f (g p)) => Monoid ((f :.: g) p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

mempty :: (f :.: g) p #

mappend :: (f :.: g) p -> (f :.: g) p -> (f :.: g) p #

mconcat :: [(f :.: g) p] -> (f :.: g) p #

Monoid (f p) => Monoid (M1 i c f p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

mempty :: M1 i c f p #

mappend :: M1 i c f p -> M1 i c f p -> M1 i c f p #

mconcat :: [M1 i c f p] -> M1 i c f p #

(Monoid a, Monoid b, Monoid c, Monoid d, Monoid e) => Monoid (a, b, c, d, e)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

mempty :: (a, b, c, d, e) #

mappend :: (a, b, c, d, e) -> (a, b, c, d, e) -> (a, b, c, d, e) #

mconcat :: [(a, b, c, d, e)] -> (a, b, c, d, e) #

class Semigroup a where #

The class of semigroups (types with an associative binary operation).

Instances should satisfy the following:

Associativity
x <> (y <> z) = (x <> y) <> z

You can alternatively define sconcat instead of (<>), in which case the laws are:

Unit
sconcat (pure x) = x
Multiplication
sconcat (join xss) = sconcat (fmap sconcat xss)

Since: base-4.9.0.0

Minimal complete definition

(<>) | sconcat

Methods

(<>) :: a -> a -> a infixr 6 #

An associative operation.

>>> [1,2,3] <> [4,5,6]
[1,2,3,4,5,6]

Instances

Instances details
Semigroup All

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: All -> All -> All #

sconcat :: NonEmpty All -> All #

stimes :: Integral b => b -> All -> All #

Semigroup Any

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Any -> Any -> Any #

sconcat :: NonEmpty Any -> Any #

stimes :: Integral b => b -> Any -> Any #

Semigroup Void

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: Void -> Void -> Void #

sconcat :: NonEmpty Void -> Void #

stimes :: Integral b => b -> Void -> Void #

Semigroup Ordering

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Semigroup ()

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: () -> () -> () #

sconcat :: NonEmpty () -> () #

stimes :: Integral b => b -> () -> () #

Semigroup a => Semigroup (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Methods

(<>) :: Identity a -> Identity a -> Identity a #

sconcat :: NonEmpty (Identity a) -> Identity a #

stimes :: Integral b => b -> Identity a -> Identity a #

Semigroup (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Monoid

Methods

(<>) :: First a -> First a -> First a #

sconcat :: NonEmpty (First a) -> First a #

stimes :: Integral b => b -> First a -> First a #

Semigroup (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Monoid

Methods

(<>) :: Last a -> Last a -> Last a #

sconcat :: NonEmpty (Last a) -> Last a #

stimes :: Integral b => b -> Last a -> Last a #

Semigroup a => Semigroup (Down a)

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

(<>) :: Down a -> Down a -> Down a #

sconcat :: NonEmpty (Down a) -> Down a #

stimes :: Integral b => b -> Down a -> Down a #

Semigroup (First a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: First a -> First a -> First a #

sconcat :: NonEmpty (First a) -> First a #

stimes :: Integral b => b -> First a -> First a #

Semigroup (Last a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: Last a -> Last a -> Last a #

sconcat :: NonEmpty (Last a) -> Last a #

stimes :: Integral b => b -> Last a -> Last a #

Ord a => Semigroup (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: Max a -> Max a -> Max a #

sconcat :: NonEmpty (Max a) -> Max a #

stimes :: Integral b => b -> Max a -> Max a #

Ord a => Semigroup (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(<>) :: Min a -> Min a -> Min a #

sconcat :: NonEmpty (Min a) -> Min a #

stimes :: Integral b => b -> Min a -> Min a #

Monoid m => Semigroup (WrappedMonoid m)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Semigroup a => Semigroup (Dual a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Dual a -> Dual a -> Dual a #

sconcat :: NonEmpty (Dual a) -> Dual a #

stimes :: Integral b => b -> Dual a -> Dual a #

Semigroup (Endo a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Endo a -> Endo a -> Endo a #

sconcat :: NonEmpty (Endo a) -> Endo a #

stimes :: Integral b => b -> Endo a -> Endo a #

Num a => Semigroup (Product a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Product a -> Product a -> Product a #

sconcat :: NonEmpty (Product a) -> Product a #

stimes :: Integral b => b -> Product a -> Product a #

Num a => Semigroup (Sum a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Sum a -> Sum a -> Sum a #

sconcat :: NonEmpty (Sum a) -> Sum a #

stimes :: Integral b => b -> Sum a -> Sum a #

Semigroup (NonEmpty a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: NonEmpty a -> NonEmpty a -> NonEmpty a #

sconcat :: NonEmpty (NonEmpty a) -> NonEmpty a #

stimes :: Integral b => b -> NonEmpty a -> NonEmpty a #

(Generic a, Semigroup (Rep a ())) => Semigroup (Generically a)

Since: base-4.17.0.0

Instance details

Defined in GHC.Generics

Semigroup p => Semigroup (Par1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: Par1 p -> Par1 p -> Par1 p #

sconcat :: NonEmpty (Par1 p) -> Par1 p #

stimes :: Integral b => b -> Par1 p -> Par1 p #

Semigroup a => Semigroup (IO a)

Since: base-4.10.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: IO a -> IO a -> IO a #

sconcat :: NonEmpty (IO a) -> IO a #

stimes :: Integral b => b -> IO a -> IO a #

Additive a => Semigroup (Sum a) Source # 
Instance details

Defined in NumHask.Algebra.Additive

Methods

(<>) :: Sum a -> Sum a -> Sum a #

sconcat :: NonEmpty (Sum a) -> Sum a #

stimes :: Integral b => b -> Sum a -> Sum a #

Multiplicative a => Semigroup (Product a) Source # 
Instance details

Defined in NumHask.Algebra.Multiplicative

Methods

(<>) :: Product a -> Product a -> Product a #

sconcat :: NonEmpty (Product a) -> Product a #

stimes :: Integral b => b -> Product a -> Product a #

Semigroup a => Semigroup (Maybe a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: Maybe a -> Maybe a -> Maybe a #

sconcat :: NonEmpty (Maybe a) -> Maybe a #

stimes :: Integral b => b -> Maybe a -> Maybe a #

Semigroup a => Semigroup (a)

Since: base-4.15

Instance details

Defined in GHC.Base

Methods

(<>) :: (a) -> (a) -> (a) #

sconcat :: NonEmpty (a) -> (a) #

stimes :: Integral b => b -> (a) -> (a) #

Semigroup [a]

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: [a] -> [a] -> [a] #

sconcat :: NonEmpty [a] -> [a] #

stimes :: Integral b => b -> [a] -> [a] #

Semigroup (Either a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Either

Methods

(<>) :: Either a b -> Either a b -> Either a b #

sconcat :: NonEmpty (Either a b) -> Either a b #

stimes :: Integral b0 => b0 -> Either a b -> Either a b #

Semigroup (U1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: U1 p -> U1 p -> U1 p #

sconcat :: NonEmpty (U1 p) -> U1 p #

stimes :: Integral b => b -> U1 p -> U1 p #

Semigroup (V1 p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: V1 p -> V1 p -> V1 p #

sconcat :: NonEmpty (V1 p) -> V1 p #

stimes :: Integral b => b -> V1 p -> V1 p #

(Semigroup a, Semigroup b) => Semigroup (a, b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b) -> (a, b) -> (a, b) #

sconcat :: NonEmpty (a, b) -> (a, b) #

stimes :: Integral b0 => b0 -> (a, b) -> (a, b) #

Semigroup b => Semigroup (a -> b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a -> b) -> (a -> b) -> a -> b #

sconcat :: NonEmpty (a -> b) -> a -> b #

stimes :: Integral b0 => b0 -> (a -> b) -> a -> b #

Semigroup a => Semigroup (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

(<>) :: Const a b -> Const a b -> Const a b #

sconcat :: NonEmpty (Const a b) -> Const a b #

stimes :: Integral b0 => b0 -> Const a b -> Const a b #

(Applicative f, Semigroup a) => Semigroup (Ap f a)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

(<>) :: Ap f a -> Ap f a -> Ap f a #

sconcat :: NonEmpty (Ap f a) -> Ap f a #

stimes :: Integral b => b -> Ap f a -> Ap f a #

Alternative f => Semigroup (Alt f a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Alt f a -> Alt f a -> Alt f a #

sconcat :: NonEmpty (Alt f a) -> Alt f a #

stimes :: Integral b => b -> Alt f a -> Alt f a #

Semigroup (f p) => Semigroup (Rec1 f p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: Rec1 f p -> Rec1 f p -> Rec1 f p #

sconcat :: NonEmpty (Rec1 f p) -> Rec1 f p #

stimes :: Integral b => b -> Rec1 f p -> Rec1 f p #

(Semigroup a, Semigroup b, Semigroup c) => Semigroup (a, b, c)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b, c) -> (a, b, c) -> (a, b, c) #

sconcat :: NonEmpty (a, b, c) -> (a, b, c) #

stimes :: Integral b0 => b0 -> (a, b, c) -> (a, b, c) #

(Semigroup (f p), Semigroup (g p)) => Semigroup ((f :*: g) p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: (f :*: g) p -> (f :*: g) p -> (f :*: g) p #

sconcat :: NonEmpty ((f :*: g) p) -> (f :*: g) p #

stimes :: Integral b => b -> (f :*: g) p -> (f :*: g) p #

Semigroup c => Semigroup (K1 i c p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: K1 i c p -> K1 i c p -> K1 i c p #

sconcat :: NonEmpty (K1 i c p) -> K1 i c p #

stimes :: Integral b => b -> K1 i c p -> K1 i c p #

(Semigroup a, Semigroup b, Semigroup c, Semigroup d) => Semigroup (a, b, c, d)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b, c, d) -> (a, b, c, d) -> (a, b, c, d) #

sconcat :: NonEmpty (a, b, c, d) -> (a, b, c, d) #

stimes :: Integral b0 => b0 -> (a, b, c, d) -> (a, b, c, d) #

Semigroup (f (g p)) => Semigroup ((f :.: g) p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: (f :.: g) p -> (f :.: g) p -> (f :.: g) p #

sconcat :: NonEmpty ((f :.: g) p) -> (f :.: g) p #

stimes :: Integral b => b -> (f :.: g) p -> (f :.: g) p #

Semigroup (f p) => Semigroup (M1 i c f p)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

(<>) :: M1 i c f p -> M1 i c f p -> M1 i c f p #

sconcat :: NonEmpty (M1 i c f p) -> M1 i c f p #

stimes :: Integral b => b -> M1 i c f p -> M1 i c f p #

(Semigroup a, Semigroup b, Semigroup c, Semigroup d, Semigroup e) => Semigroup (a, b, c, d, e)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(<>) :: (a, b, c, d, e) -> (a, b, c, d, e) -> (a, b, c, d, e) #

sconcat :: NonEmpty (a, b, c, d, e) -> (a, b, c, d, e) #

stimes :: Integral b0 => b0 -> (a, b, c, d, e) -> (a, b, c, d, e) #

class Functor f => Applicative (f :: Type -> Type) where #

A functor with application, providing operations to

  • embed pure expressions (pure), and
  • sequence computations and combine their results (<*> and liftA2).

A minimal complete definition must include implementations of pure and of either <*> or liftA2. If it defines both, then they must behave the same as their default definitions:

(<*>) = liftA2 id
liftA2 f x y = f <$> x <*> y

Further, any definition must satisfy the following:

Identity
pure id <*> v = v
Composition
pure (.) <*> u <*> v <*> w = u <*> (v <*> w)
Homomorphism
pure f <*> pure x = pure (f x)
Interchange
u <*> pure y = pure ($ y) <*> u

The other methods have the following default definitions, which may be overridden with equivalent specialized implementations:

As a consequence of these laws, the Functor instance for f will satisfy

It may be useful to note that supposing

forall x y. p (q x y) = f x . g y

it follows from the above that

liftA2 p (liftA2 q u v) = liftA2 f u . liftA2 g v

If f is also a Monad, it should satisfy

(which implies that pure and <*> satisfy the applicative functor laws).

Minimal complete definition

pure, ((<*>) | liftA2)

Methods

pure :: a -> f a #

Lift a value.

(<*>) :: f (a -> b) -> f a -> f b infixl 4 #

Sequential application.

A few functors support an implementation of <*> that is more efficient than the default one.

Example

Expand

Used in combination with (<$>), (<*>) can be used to build a record.

>>> data MyState = MyState {arg1 :: Foo, arg2 :: Bar, arg3 :: Baz}
>>> produceFoo :: Applicative f => f Foo
>>> produceBar :: Applicative f => f Bar
>>> produceBaz :: Applicative f => f Baz
>>> mkState :: Applicative f => f MyState
>>> mkState = MyState <$> produceFoo <*> produceBar <*> produceBaz

liftA2 :: (a -> b -> c) -> f a -> f b -> f c #

Lift a binary function to actions.

Some functors support an implementation of liftA2 that is more efficient than the default one. In particular, if fmap is an expensive operation, it is likely better to use liftA2 than to fmap over the structure and then use <*>.

This became a typeclass method in 4.10.0.0. Prior to that, it was a function defined in terms of <*> and fmap.

Example

Expand
>>> liftA2 (,) (Just 3) (Just 5)
Just (3,5)

(*>) :: f a -> f b -> f b infixl 4 #

Sequence actions, discarding the value of the first argument.

Examples

Expand

If used in conjunction with the Applicative instance for Maybe, you can chain Maybe computations, with a possible "early return" in case of Nothing.

>>> Just 2 *> Just 3
Just 3
>>> Nothing *> Just 3
Nothing

Of course a more interesting use case would be to have effectful computations instead of just returning pure values.

>>> import Data.Char
>>> import Text.ParserCombinators.ReadP
>>> let p = string "my name is " *> munch1 isAlpha <* eof
>>> readP_to_S p "my name is Simon"
[("Simon","")]

(<*) :: f a -> f b -> f a infixl 4 #

Sequence actions, discarding the value of the second argument.

Instances

Instances details
Applicative ZipList
f <$> ZipList xs1 <*> ... <*> ZipList xsN
    = ZipList (zipWithN f xs1 ... xsN)

where zipWithN refers to the zipWith function of the appropriate arity (zipWith, zipWith3, zipWith4, ...). For example:

(\a b c -> stimes c [a, b]) <$> ZipList "abcd" <*> ZipList "567" <*> ZipList [1..]
    = ZipList (zipWith3 (\a b c -> stimes c [a, b]) "abcd" "567" [1..])
    = ZipList {getZipList = ["a5","b6b6","c7c7c7"]}

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

pure :: a -> ZipList a #

(<*>) :: ZipList (a -> b) -> ZipList a -> ZipList b #

liftA2 :: (a -> b -> c) -> ZipList a -> ZipList b -> ZipList c #

(*>) :: ZipList a -> ZipList b -> ZipList b #

(<*) :: ZipList a -> ZipList b -> ZipList a #

Applicative Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

pure :: a -> Identity a #

(<*>) :: Identity (a -> b) -> Identity a -> Identity b #

liftA2 :: (a -> b -> c) -> Identity a -> Identity b -> Identity c #

(*>) :: Identity a -> Identity b -> Identity b #

(<*) :: Identity a -> Identity b -> Identity a #

Applicative First

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

pure :: a -> First a #

(<*>) :: First (a -> b) -> First a -> First b #

liftA2 :: (a -> b -> c) -> First a -> First b -> First c #

(*>) :: First a -> First b -> First b #

(<*) :: First a -> First b -> First a #

Applicative Last

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

pure :: a -> Last a #

(<*>) :: Last (a -> b) -> Last a -> Last b #

liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c #

(*>) :: Last a -> Last b -> Last b #

(<*) :: Last a -> Last b -> Last a #

Applicative Down

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

pure :: a -> Down a #

(<*>) :: Down (a -> b) -> Down a -> Down b #

liftA2 :: (a -> b -> c) -> Down a -> Down b -> Down c #

(*>) :: Down a -> Down b -> Down b #

(<*) :: Down a -> Down b -> Down a #

Applicative First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> First a #

(<*>) :: First (a -> b) -> First a -> First b #

liftA2 :: (a -> b -> c) -> First a -> First b -> First c #

(*>) :: First a -> First b -> First b #

(<*) :: First a -> First b -> First a #

Applicative Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Last a #

(<*>) :: Last (a -> b) -> Last a -> Last b #

liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c #

(*>) :: Last a -> Last b -> Last b #

(<*) :: Last a -> Last b -> Last a #

Applicative Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Max a #

(<*>) :: Max (a -> b) -> Max a -> Max b #

liftA2 :: (a -> b -> c) -> Max a -> Max b -> Max c #

(*>) :: Max a -> Max b -> Max b #

(<*) :: Max a -> Max b -> Max a #

Applicative Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Min a #

(<*>) :: Min (a -> b) -> Min a -> Min b #

liftA2 :: (a -> b -> c) -> Min a -> Min b -> Min c #

(*>) :: Min a -> Min b -> Min b #

(<*) :: Min a -> Min b -> Min a #

Applicative Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Dual a #

(<*>) :: Dual (a -> b) -> Dual a -> Dual b #

liftA2 :: (a -> b -> c) -> Dual a -> Dual b -> Dual c #

(*>) :: Dual a -> Dual b -> Dual b #

(<*) :: Dual a -> Dual b -> Dual a #

Applicative Product

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Product a #

(<*>) :: Product (a -> b) -> Product a -> Product b #

liftA2 :: (a -> b -> c) -> Product a -> Product b -> Product c #

(*>) :: Product a -> Product b -> Product b #

(<*) :: Product a -> Product b -> Product a #

Applicative Sum

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Sum a #

(<*>) :: Sum (a -> b) -> Sum a -> Sum b #

liftA2 :: (a -> b -> c) -> Sum a -> Sum b -> Sum c #

(*>) :: Sum a -> Sum b -> Sum b #

(<*) :: Sum a -> Sum b -> Sum a #

Applicative NonEmpty

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

pure :: a -> NonEmpty a #

(<*>) :: NonEmpty (a -> b) -> NonEmpty a -> NonEmpty b #

liftA2 :: (a -> b -> c) -> NonEmpty a -> NonEmpty b -> NonEmpty c #

(*>) :: NonEmpty a -> NonEmpty b -> NonEmpty b #

(<*) :: NonEmpty a -> NonEmpty b -> NonEmpty a #

Applicative Par1

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> Par1 a #

(<*>) :: Par1 (a -> b) -> Par1 a -> Par1 b #

liftA2 :: (a -> b -> c) -> Par1 a -> Par1 b -> Par1 c #

(*>) :: Par1 a -> Par1 b -> Par1 b #

(<*) :: Par1 a -> Par1 b -> Par1 a #

Applicative P

Since: base-4.5.0.0

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

pure :: a -> P a #

(<*>) :: P (a -> b) -> P a -> P b #

liftA2 :: (a -> b -> c) -> P a -> P b -> P c #

(*>) :: P a -> P b -> P b #

(<*) :: P a -> P b -> P a #

Applicative ReadP

Since: base-4.6.0.0

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

pure :: a -> ReadP a #

(<*>) :: ReadP (a -> b) -> ReadP a -> ReadP b #

liftA2 :: (a -> b -> c) -> ReadP a -> ReadP b -> ReadP c #

(*>) :: ReadP a -> ReadP b -> ReadP b #

(<*) :: ReadP a -> ReadP b -> ReadP a #

Applicative ReadPrec

Since: base-4.6.0.0

Instance details

Defined in Text.ParserCombinators.ReadPrec

Methods

pure :: a -> ReadPrec a #

(<*>) :: ReadPrec (a -> b) -> ReadPrec a -> ReadPrec b #

liftA2 :: (a -> b -> c) -> ReadPrec a -> ReadPrec b -> ReadPrec c #

(*>) :: ReadPrec a -> ReadPrec b -> ReadPrec b #

(<*) :: ReadPrec a -> ReadPrec b -> ReadPrec a #

Applicative IO

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> IO a #

(<*>) :: IO (a -> b) -> IO a -> IO b #

liftA2 :: (a -> b -> c) -> IO a -> IO b -> IO c #

(*>) :: IO a -> IO b -> IO b #

(<*) :: IO a -> IO b -> IO a #

Applicative EuclideanPair Source # 
Instance details

Defined in NumHask.Algebra.Metric

Applicative Maybe

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> Maybe a #

(<*>) :: Maybe (a -> b) -> Maybe a -> Maybe b #

liftA2 :: (a -> b -> c) -> Maybe a -> Maybe b -> Maybe c #

(*>) :: Maybe a -> Maybe b -> Maybe b #

(<*) :: Maybe a -> Maybe b -> Maybe a #

Applicative Solo

Since: base-4.15

Instance details

Defined in GHC.Base

Methods

pure :: a -> Solo a #

(<*>) :: Solo (a -> b) -> Solo a -> Solo b #

liftA2 :: (a -> b -> c) -> Solo a -> Solo b -> Solo c #

(*>) :: Solo a -> Solo b -> Solo b #

(<*) :: Solo a -> Solo b -> Solo a #

Applicative List

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> [a] #

(<*>) :: [a -> b] -> [a] -> [b] #

liftA2 :: (a -> b -> c) -> [a] -> [b] -> [c] #

(*>) :: [a] -> [b] -> [b] #

(<*) :: [a] -> [b] -> [a] #

Monad m => Applicative (WrappedMonad m)

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

pure :: a -> WrappedMonad m a #

(<*>) :: WrappedMonad m (a -> b) -> WrappedMonad m a -> WrappedMonad m b #

liftA2 :: (a -> b -> c) -> WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m c #

(*>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b #

(<*) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m a #

Arrow a => Applicative (ArrowMonad a)

Since: base-4.6.0.0

Instance details

Defined in Control.Arrow

Methods

pure :: a0 -> ArrowMonad a a0 #

(<*>) :: ArrowMonad a (a0 -> b) -> ArrowMonad a a0 -> ArrowMonad a b #

liftA2 :: (a0 -> b -> c) -> ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a c #

(*>) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a b #

(<*) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a a0 #

Applicative (Either e)

Since: base-3.0

Instance details

Defined in Data.Either

Methods

pure :: a -> Either e a #

(<*>) :: Either e (a -> b) -> Either e a -> Either e b #

liftA2 :: (a -> b -> c) -> Either e a -> Either e b -> Either e c #

(*>) :: Either e a -> Either e b -> Either e b #

(<*) :: Either e a -> Either e b -> Either e a #

Applicative (U1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> U1 a #

(<*>) :: U1 (a -> b) -> U1 a -> U1 b #

liftA2 :: (a -> b -> c) -> U1 a -> U1 b -> U1 c #

(*>) :: U1 a -> U1 b -> U1 b #

(<*) :: U1 a -> U1 b -> U1 a #

Monoid a => Applicative ((,) a)

For tuples, the Monoid constraint on a determines how the first values merge. For example, Strings concatenate:

("hello ", (+15)) <*> ("world!", 2002)
("hello world!",2017)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a0 -> (a, a0) #

(<*>) :: (a, a0 -> b) -> (a, a0) -> (a, b) #

liftA2 :: (a0 -> b -> c) -> (a, a0) -> (a, b) -> (a, c) #

(*>) :: (a, a0) -> (a, b) -> (a, b) #

(<*) :: (a, a0) -> (a, b) -> (a, a0) #

Arrow a => Applicative (WrappedArrow a b)

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

pure :: a0 -> WrappedArrow a b a0 #

(<*>) :: WrappedArrow a b (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 #

liftA2 :: (a0 -> b0 -> c) -> WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b c #

(*>) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b b0 #

(<*) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 #

Applicative m => Applicative (Kleisli m a)

Since: base-4.14.0.0

Instance details

Defined in Control.Arrow

Methods

pure :: a0 -> Kleisli m a a0 #

(<*>) :: Kleisli m a (a0 -> b) -> Kleisli m a a0 -> Kleisli m a b #

liftA2 :: (a0 -> b -> c) -> Kleisli m a a0 -> Kleisli m a b -> Kleisli m a c #

(*>) :: Kleisli m a a0 -> Kleisli m a b -> Kleisli m a b #

(<*) :: Kleisli m a a0 -> Kleisli m a b -> Kleisli m a a0 #

Monoid m => Applicative (Const m :: Type -> Type)

Since: base-2.0.1

Instance details

Defined in Data.Functor.Const

Methods

pure :: a -> Const m a #

(<*>) :: Const m (a -> b) -> Const m a -> Const m b #

liftA2 :: (a -> b -> c) -> Const m a -> Const m b -> Const m c #

(*>) :: Const m a -> Const m b -> Const m b #

(<*) :: Const m a -> Const m b -> Const m a #

Applicative f => Applicative (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

pure :: a -> Ap f a #

(<*>) :: Ap f (a -> b) -> Ap f a -> Ap f b #

liftA2 :: (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c #

(*>) :: Ap f a -> Ap f b -> Ap f b #

(<*) :: Ap f a -> Ap f b -> Ap f a #

Applicative f => Applicative (Alt f)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Alt f a #

(<*>) :: Alt f (a -> b) -> Alt f a -> Alt f b #

liftA2 :: (a -> b -> c) -> Alt f a -> Alt f b -> Alt f c #

(*>) :: Alt f a -> Alt f b -> Alt f b #

(<*) :: Alt f a -> Alt f b -> Alt f a #

(Generic1 f, Applicative (Rep1 f)) => Applicative (Generically1 f)

Since: base-4.17.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> Generically1 f a #

(<*>) :: Generically1 f (a -> b) -> Generically1 f a -> Generically1 f b #

liftA2 :: (a -> b -> c) -> Generically1 f a -> Generically1 f b -> Generically1 f c #

(*>) :: Generically1 f a -> Generically1 f b -> Generically1 f b #

(<*) :: Generically1 f a -> Generically1 f b -> Generically1 f a #

Applicative f => Applicative (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> Rec1 f a #

(<*>) :: Rec1 f (a -> b) -> Rec1 f a -> Rec1 f b #

liftA2 :: (a -> b -> c) -> Rec1 f a -> Rec1 f b -> Rec1 f c #

(*>) :: Rec1 f a -> Rec1 f b -> Rec1 f b #

(<*) :: Rec1 f a -> Rec1 f b -> Rec1 f a #

(Monoid a, Monoid b) => Applicative ((,,) a b)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

pure :: a0 -> (a, b, a0) #

(<*>) :: (a, b, a0 -> b0) -> (a, b, a0) -> (a, b, b0) #

liftA2 :: (a0 -> b0 -> c) -> (a, b, a0) -> (a, b, b0) -> (a, b, c) #

(*>) :: (a, b, a0) -> (a, b, b0) -> (a, b, b0) #

(<*) :: (a, b, a0) -> (a, b, b0) -> (a, b, a0) #

(Applicative f, Applicative g) => Applicative (f :*: g)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> (f :*: g) a #

(<*>) :: (f :*: g) (a -> b) -> (f :*: g) a -> (f :*: g) b #

liftA2 :: (a -> b -> c) -> (f :*: g) a -> (f :*: g) b -> (f :*: g) c #

(*>) :: (f :*: g) a -> (f :*: g) b -> (f :*: g) b #

(<*) :: (f :*: g) a -> (f :*: g) b -> (f :*: g) a #

Monoid c => Applicative (K1 i c :: Type -> Type)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> K1 i c a #

(<*>) :: K1 i c (a -> b) -> K1 i c a -> K1 i c b #

liftA2 :: (a -> b -> c0) -> K1 i c a -> K1 i c b -> K1 i c c0 #

(*>) :: K1 i c a -> K1 i c b -> K1 i c b #

(<*) :: K1 i c a -> K1 i c b -> K1 i c a #

(Monoid a, Monoid b, Monoid c) => Applicative ((,,,) a b c)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

pure :: a0 -> (a, b, c, a0) #

(<*>) :: (a, b, c, a0 -> b0) -> (a, b, c, a0) -> (a, b, c, b0) #

liftA2 :: (a0 -> b0 -> c0) -> (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, c0) #

(*>) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, b0) #

(<*) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, a0) #

Applicative ((->) r)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> r -> a #

(<*>) :: (r -> (a -> b)) -> (r -> a) -> r -> b #

liftA2 :: (a -> b -> c) -> (r -> a) -> (r -> b) -> r -> c #

(*>) :: (r -> a) -> (r -> b) -> r -> b #

(<*) :: (r -> a) -> (r -> b) -> r -> a #

(Applicative f, Applicative g) => Applicative (f :.: g)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> (f :.: g) a #

(<*>) :: (f :.: g) (a -> b) -> (f :.: g) a -> (f :.: g) b #

liftA2 :: (a -> b -> c) -> (f :.: g) a -> (f :.: g) b -> (f :.: g) c #

(*>) :: (f :.: g) a -> (f :.: g) b -> (f :.: g) b #

(<*) :: (f :.: g) a -> (f :.: g) b -> (f :.: g) a #

Applicative f => Applicative (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> M1 i c f a #

(<*>) :: M1 i c f (a -> b) -> M1 i c f a -> M1 i c f b #

liftA2 :: (a -> b -> c0) -> M1 i c f a -> M1 i c f b -> M1 i c f c0 #

(*>) :: M1 i c f a -> M1 i c f b -> M1 i c f b #

(<*) :: M1 i c f a -> M1 i c f b -> M1 i c f a #

class Functor (f :: Type -> Type) where #

A type f is a Functor if it provides a function fmap which, given any types a and b lets you apply any function from (a -> b) to turn an f a into an f b, preserving the structure of f. Furthermore f needs to adhere to the following:

Identity
fmap id == id
Composition
fmap (f . g) == fmap f . fmap g

Note, that the second law follows from the free theorem of the type fmap and the first law, so you need only check that the former condition holds. See https://www.schoolofhaskell.com/user/edwardk/snippets/fmap or https://github.com/quchen/articles/blob/master/second_functor_law.md for an explanation.

Minimal complete definition

fmap

Methods

fmap :: (a -> b) -> f a -> f b #

fmap is used to apply a function of type (a -> b) to a value of type f a, where f is a functor, to produce a value of type f b. Note that for any type constructor with more than one parameter (e.g., Either), only the last type parameter can be modified with fmap (e.g., b in `Either a b`).

Some type constructors with two parameters or more have a Bifunctor instance that allows both the last and the penultimate parameters to be mapped over.

Examples

Expand

Convert from a Maybe Int to a Maybe String using show:

>>> fmap show Nothing
Nothing
>>> fmap show (Just 3)
Just "3"

Convert from an Either Int Int to an Either Int String using show:

>>> fmap show (Left 17)
Left 17
>>> fmap show (Right 17)
Right "17"

Double each element of a list:

>>> fmap (*2) [1,2,3]
[2,4,6]

Apply even to the second element of a pair:

>>> fmap even (2,2)
(2,True)

It may seem surprising that the function is only applied to the last element of the tuple compared to the list example above which applies it to every element in the list. To understand, remember that tuples are type constructors with multiple type parameters: a tuple of 3 elements (a,b,c) can also be written (,,) a b c and its Functor instance is defined for Functor ((,,) a b) (i.e., only the third parameter is free to be mapped over with fmap).

It explains why fmap can be used with tuples containing values of different types as in the following example:

>>> fmap even ("hello", 1.0, 4)
("hello",1.0,True)

(<$) :: a -> f b -> f a infixl 4 #

Replace all locations in the input with the same value. The default definition is fmap . const, but this may be overridden with a more efficient version.

Examples

Expand

Perform a computation with Maybe and replace the result with a constant value if it is Just:

>>> 'a' <$ Just 2
Just 'a'
>>> 'a' <$ Nothing
Nothing

Instances

Instances details
Functor ZipList

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

fmap :: (a -> b) -> ZipList a -> ZipList b #

(<$) :: a -> ZipList b -> ZipList a #

Functor Handler

Since: base-4.6.0.0

Instance details

Defined in Control.Exception

Methods

fmap :: (a -> b) -> Handler a -> Handler b #

(<$) :: a -> Handler b -> Handler a #

Functor Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

fmap :: (a -> b) -> Identity a -> Identity b #

(<$) :: a -> Identity b -> Identity a #

Functor First

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

fmap :: (a -> b) -> First a -> First b #

(<$) :: a -> First b -> First a #

Functor Last

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

fmap :: (a -> b) -> Last a -> Last b #

(<$) :: a -> Last b -> Last a #

Functor Down

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

fmap :: (a -> b) -> Down a -> Down b #

(<$) :: a -> Down b -> Down a #

Functor First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a -> b) -> First a -> First b #

(<$) :: a -> First b -> First a #

Functor Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a -> b) -> Last a -> Last b #

(<$) :: a -> Last b -> Last a #

Functor Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a -> b) -> Max a -> Max b #

(<$) :: a -> Max b -> Max a #

Functor Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a -> b) -> Min a -> Min b #

(<$) :: a -> Min b -> Min a #

Functor Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

fmap :: (a -> b) -> Dual a -> Dual b #

(<$) :: a -> Dual b -> Dual a #

Functor Product

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

fmap :: (a -> b) -> Product a -> Product b #

(<$) :: a -> Product b -> Product a #

Functor Sum

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

fmap :: (a -> b) -> Sum a -> Sum b #

(<$) :: a -> Sum b -> Sum a #

Functor NonEmpty

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> NonEmpty a -> NonEmpty b #

(<$) :: a -> NonEmpty b -> NonEmpty a #

Functor Par1

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> Par1 a -> Par1 b #

(<$) :: a -> Par1 b -> Par1 a #

Functor P

Since: base-4.8.0.0

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

fmap :: (a -> b) -> P a -> P b #

(<$) :: a -> P b -> P a #

Functor ReadP

Since: base-2.1

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

fmap :: (a -> b) -> ReadP a -> ReadP b #

(<$) :: a -> ReadP b -> ReadP a #

Functor ReadPrec

Since: base-2.1

Instance details

Defined in Text.ParserCombinators.ReadPrec

Methods

fmap :: (a -> b) -> ReadPrec a -> ReadPrec b #

(<$) :: a -> ReadPrec b -> ReadPrec a #

Functor IO

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> IO a -> IO b #

(<$) :: a -> IO b -> IO a #

Functor EuclideanPair Source # 
Instance details

Defined in NumHask.Algebra.Metric

Methods

fmap :: (a -> b) -> EuclideanPair a -> EuclideanPair b #

(<$) :: a -> EuclideanPair b -> EuclideanPair a #

Functor Complex Source # 
Instance details

Defined in NumHask.Data.Complex

Methods

fmap :: (a -> b) -> Complex a -> Complex b #

(<$) :: a -> Complex b -> Complex a #

Functor Maybe

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> Maybe a -> Maybe b #

(<$) :: a -> Maybe b -> Maybe a #

Functor Solo

Since: base-4.15

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> Solo a -> Solo b #

(<$) :: a -> Solo b -> Solo a #

Functor List

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> [a] -> [b] #

(<$) :: a -> [b] -> [a] #

Monad m => Functor (WrappedMonad m)

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

fmap :: (a -> b) -> WrappedMonad m a -> WrappedMonad m b #

(<$) :: a -> WrappedMonad m b -> WrappedMonad m a #

Arrow a => Functor (ArrowMonad a)

Since: base-4.6.0.0

Instance details

Defined in Control.Arrow

Methods

fmap :: (a0 -> b) -> ArrowMonad a a0 -> ArrowMonad a b #

(<$) :: a0 -> ArrowMonad a b -> ArrowMonad a a0 #

Functor (Either a)

Since: base-3.0

Instance details

Defined in Data.Either

Methods

fmap :: (a0 -> b) -> Either a a0 -> Either a b #

(<$) :: a0 -> Either a b -> Either a a0 #

Functor (Arg a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fmap :: (a0 -> b) -> Arg a a0 -> Arg a b #

(<$) :: a0 -> Arg a b -> Arg a a0 #

Functor (U1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> U1 a -> U1 b #

(<$) :: a -> U1 b -> U1 a #

Functor (V1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> V1 a -> V1 b #

(<$) :: a -> V1 b -> V1 a #

Functor ((,) a)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

fmap :: (a0 -> b) -> (a, a0) -> (a, b) #

(<$) :: a0 -> (a, b) -> (a, a0) #

Arrow a => Functor (WrappedArrow a b)

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

fmap :: (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 #

(<$) :: a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 #

Functor m => Functor (Kleisli m a)

Since: base-4.14.0.0

Instance details

Defined in Control.Arrow

Methods

fmap :: (a0 -> b) -> Kleisli m a a0 -> Kleisli m a b #

(<$) :: a0 -> Kleisli m a b -> Kleisli m a a0 #

Functor (Const m :: Type -> Type)

Since: base-2.1

Instance details

Defined in Data.Functor.Const

Methods

fmap :: (a -> b) -> Const m a -> Const m b #

(<$) :: a -> Const m b -> Const m a #

Functor f => Functor (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

fmap :: (a -> b) -> Ap f a -> Ap f b #

(<$) :: a -> Ap f b -> Ap f a #

Functor f => Functor (Alt f)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

fmap :: (a -> b) -> Alt f a -> Alt f b #

(<$) :: a -> Alt f b -> Alt f a #

(Generic1 f, Functor (Rep1 f)) => Functor (Generically1 f)

Since: base-4.17.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> Generically1 f a -> Generically1 f b #

(<$) :: a -> Generically1 f b -> Generically1 f a #

Functor f => Functor (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> Rec1 f a -> Rec1 f b #

(<$) :: a -> Rec1 f b -> Rec1 f a #

Functor (URec (Ptr ()) :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec (Ptr ()) a -> URec (Ptr ()) b #

(<$) :: a -> URec (Ptr ()) b -> URec (Ptr ()) a #

Functor (URec Char :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Char a -> URec Char b #

(<$) :: a -> URec Char b -> URec Char a #

Functor (URec Double :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Double a -> URec Double b #

(<$) :: a -> URec Double b -> URec Double a #

Functor (URec Float :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Float a -> URec Float b #

(<$) :: a -> URec Float b -> URec Float a #

Functor (URec Int :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Int a -> URec Int b #

(<$) :: a -> URec Int b -> URec Int a #

Functor (URec Word :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> URec Word a -> URec Word b #

(<$) :: a -> URec Word b -> URec Word a #

Functor ((,,) a b)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

fmap :: (a0 -> b0) -> (a, b, a0) -> (a, b, b0) #

(<$) :: a0 -> (a, b, b0) -> (a, b, a0) #

(Functor f, Functor g) => Functor (f :*: g)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> (f :*: g) a -> (f :*: g) b #

(<$) :: a -> (f :*: g) b -> (f :*: g) a #

(Functor f, Functor g) => Functor (f :+: g)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> (f :+: g) a -> (f :+: g) b #

(<$) :: a -> (f :+: g) b -> (f :+: g) a #

Functor (K1 i c :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> K1 i c a -> K1 i c b #

(<$) :: a -> K1 i c b -> K1 i c a #

Functor ((,,,) a b c)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

fmap :: (a0 -> b0) -> (a, b, c, a0) -> (a, b, c, b0) #

(<$) :: a0 -> (a, b, c, b0) -> (a, b, c, a0) #

Functor ((->) r)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

fmap :: (a -> b) -> (r -> a) -> r -> b #

(<$) :: a -> (r -> b) -> r -> a #

(Functor f, Functor g) => Functor (f :.: g)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> (f :.: g) a -> (f :.: g) b #

(<$) :: a -> (f :.: g) b -> (f :.: g) a #

Functor f => Functor (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

fmap :: (a -> b) -> M1 i c f a -> M1 i c f b #

(<$) :: a -> M1 i c f b -> M1 i c f a #

Functor ((,,,,) a b c d)

Since: base-4.18.0.0

Instance details

Defined in GHC.Base

Methods

fmap :: (a0 -> b0) -> (a, b, c, d, a0) -> (a, b, c, d, b0) #

(<$) :: a0 -> (a, b, c, d, b0) -> (a, b, c, d, a0) #

Functor ((,,,,,) a b c d e)

Since: base-4.18.0.0

Instance details

Defined in GHC.Base

Methods

fmap :: (a0 -> b0) -> (a, b, c, d, e, a0) -> (a, b, c, d, e, b0) #

(<$) :: a0 -> (a, b, c, d, e, b0) -> (a, b, c, d, e, a0) #

Functor ((,,,,,,) a b c d e f)

Since: base-4.18.0.0

Instance details

Defined in GHC.Base

Methods

fmap :: (a0 -> b0) -> (a, b, c, d, e, f, a0) -> (a, b, c, d, e, f, b0) #

(<$) :: a0 -> (a, b, c, d, e, f, b0) -> (a, b, c, d, e, f, a0) #

class Applicative m => Monad (m :: Type -> Type) where #

The Monad class defines the basic operations over a monad, a concept from a branch of mathematics known as category theory. From the perspective of a Haskell programmer, however, it is best to think of a monad as an abstract datatype of actions. Haskell's do expressions provide a convenient syntax for writing monadic expressions.

Instances of Monad should satisfy the following:

Left identity
return a >>= k = k a
Right identity
m >>= return = m
Associativity
m >>= (\x -> k x >>= h) = (m >>= k) >>= h

Furthermore, the Monad and Applicative operations should relate as follows:

The above laws imply:

and that pure and (<*>) satisfy the applicative functor laws.

The instances of Monad for lists, Maybe and IO defined in the Prelude satisfy these laws.

Minimal complete definition

(>>=)

Methods

(>>=) :: m a -> (a -> m b) -> m b infixl 1 #

Sequentially compose two actions, passing any value produced by the first as an argument to the second.

'as >>= bs' can be understood as the do expression

do a <- as
   bs a

(>>) :: m a -> m b -> m b infixl 1 #

Sequentially compose two actions, discarding any value produced by the first, like sequencing operators (such as the semicolon) in imperative languages.

'as >> bs' can be understood as the do expression

do as
   bs

return :: a -> m a #

Inject a value into the monadic type.

Instances

Instances details
Monad Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

(>>=) :: Identity a -> (a -> Identity b) -> Identity b #

(>>) :: Identity a -> Identity b -> Identity b #

return :: a -> Identity a #

Monad First

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

(>>=) :: First a -> (a -> First b) -> First b #

(>>) :: First a -> First b -> First b #

return :: a -> First a #

Monad Last

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

(>>=) :: Last a -> (a -> Last b) -> Last b #

(>>) :: Last a -> Last b -> Last b #

return :: a -> Last a #

Monad Down

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

(>>=) :: Down a -> (a -> Down b) -> Down b #

(>>) :: Down a -> Down b -> Down b #

return :: a -> Down a #

Monad First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(>>=) :: First a -> (a -> First b) -> First b #

(>>) :: First a -> First b -> First b #

return :: a -> First a #

Monad Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(>>=) :: Last a -> (a -> Last b) -> Last b #

(>>) :: Last a -> Last b -> Last b #

return :: a -> Last a #

Monad Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(>>=) :: Max a -> (a -> Max b) -> Max b #

(>>) :: Max a -> Max b -> Max b #

return :: a -> Max a #

Monad Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(>>=) :: Min a -> (a -> Min b) -> Min b #

(>>) :: Min a -> Min b -> Min b #

return :: a -> Min a #

Monad Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(>>=) :: Dual a -> (a -> Dual b) -> Dual b #

(>>) :: Dual a -> Dual b -> Dual b #

return :: a -> Dual a #

Monad Product

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(>>=) :: Product a -> (a -> Product b) -> Product b #

(>>) :: Product a -> Product b -> Product b #

return :: a -> Product a #

Monad Sum

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(>>=) :: Sum a -> (a -> Sum b) -> Sum b #

(>>) :: Sum a -> Sum b -> Sum b #

return :: a -> Sum a #

Monad NonEmpty

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(>>=) :: NonEmpty a -> (a -> NonEmpty b) -> NonEmpty b #

(>>) :: NonEmpty a -> NonEmpty b -> NonEmpty b #

return :: a -> NonEmpty a #

Monad Par1

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(>>=) :: Par1 a -> (a -> Par1 b) -> Par1 b #

(>>) :: Par1 a -> Par1 b -> Par1 b #

return :: a -> Par1 a #

Monad P

Since: base-2.1

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

(>>=) :: P a -> (a -> P b) -> P b #

(>>) :: P a -> P b -> P b #

return :: a -> P a #

Monad ReadP

Since: base-2.1

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

(>>=) :: ReadP a -> (a -> ReadP b) -> ReadP b #

(>>) :: ReadP a -> ReadP b -> ReadP b #

return :: a -> ReadP a #

Monad ReadPrec

Since: base-2.1

Instance details

Defined in Text.ParserCombinators.ReadPrec

Methods

(>>=) :: ReadPrec a -> (a -> ReadPrec b) -> ReadPrec b #

(>>) :: ReadPrec a -> ReadPrec b -> ReadPrec b #

return :: a -> ReadPrec a #

Monad IO

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

(>>=) :: IO a -> (a -> IO b) -> IO b #

(>>) :: IO a -> IO b -> IO b #

return :: a -> IO a #

Monad Maybe

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

(>>=) :: Maybe a -> (a -> Maybe b) -> Maybe b #

(>>) :: Maybe a -> Maybe b -> Maybe b #

return :: a -> Maybe a #

Monad Solo

Since: base-4.15

Instance details

Defined in GHC.Base

Methods

(>>=) :: Solo a -> (a -> Solo b) -> Solo b #

(>>) :: Solo a -> Solo b -> Solo b #

return :: a -> Solo a #

Monad List

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

(>>=) :: [a] -> (a -> [b]) -> [b] #

(>>) :: [a] -> [b] -> [b] #

return :: a -> [a] #

Monad m => Monad (WrappedMonad m)

Since: base-4.7.0.0

Instance details

Defined in Control.Applicative

Methods

(>>=) :: WrappedMonad m a -> (a -> WrappedMonad m b) -> WrappedMonad m b #

(>>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b #

return :: a -> WrappedMonad m a #

ArrowApply a => Monad (ArrowMonad a)

Since: base-2.1

Instance details

Defined in Control.Arrow

Methods

(>>=) :: ArrowMonad a a0 -> (a0 -> ArrowMonad a b) -> ArrowMonad a b #

(>>) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a b #

return :: a0 -> ArrowMonad a a0 #

Monad (Either e)

Since: base-4.4.0.0

Instance details

Defined in Data.Either

Methods

(>>=) :: Either e a -> (a -> Either e b) -> Either e b #

(>>) :: Either e a -> Either e b -> Either e b #

return :: a -> Either e a #

Monad (U1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(>>=) :: U1 a -> (a -> U1 b) -> U1 b #

(>>) :: U1 a -> U1 b -> U1 b #

return :: a -> U1 a #

Monoid a => Monad ((,) a)

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

(>>=) :: (a, a0) -> (a0 -> (a, b)) -> (a, b) #

(>>) :: (a, a0) -> (a, b) -> (a, b) #

return :: a0 -> (a, a0) #

Monad m => Monad (Kleisli m a)

Since: base-4.14.0.0

Instance details

Defined in Control.Arrow

Methods

(>>=) :: Kleisli m a a0 -> (a0 -> Kleisli m a b) -> Kleisli m a b #

(>>) :: Kleisli m a a0 -> Kleisli m a b -> Kleisli m a b #

return :: a0 -> Kleisli m a a0 #

Monad f => Monad (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

(>>=) :: Ap f a -> (a -> Ap f b) -> Ap f b #

(>>) :: Ap f a -> Ap f b -> Ap f b #

return :: a -> Ap f a #

Monad f => Monad (Alt f)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(>>=) :: Alt f a -> (a -> Alt f b) -> Alt f b #

(>>) :: Alt f a -> Alt f b -> Alt f b #

return :: a -> Alt f a #

Monad f => Monad (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(>>=) :: Rec1 f a -> (a -> Rec1 f b) -> Rec1 f b #

(>>) :: Rec1 f a -> Rec1 f b -> Rec1 f b #

return :: a -> Rec1 f a #

(Monoid a, Monoid b) => Monad ((,,) a b)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

(>>=) :: (a, b, a0) -> (a0 -> (a, b, b0)) -> (a, b, b0) #

(>>) :: (a, b, a0) -> (a, b, b0) -> (a, b, b0) #

return :: a0 -> (a, b, a0) #

(Monad f, Monad g) => Monad (f :*: g)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(>>=) :: (f :*: g) a -> (a -> (f :*: g) b) -> (f :*: g) b #

(>>) :: (f :*: g) a -> (f :*: g) b -> (f :*: g) b #

return :: a -> (f :*: g) a #

(Monoid a, Monoid b, Monoid c) => Monad ((,,,) a b c)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

(>>=) :: (a, b, c, a0) -> (a0 -> (a, b, c, b0)) -> (a, b, c, b0) #

(>>) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, b0) #

return :: a0 -> (a, b, c, a0) #

Monad ((->) r)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

(>>=) :: (r -> a) -> (a -> r -> b) -> r -> b #

(>>) :: (r -> a) -> (r -> b) -> r -> b #

return :: a -> r -> a #

Monad f => Monad (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

(>>=) :: M1 i c f a -> (a -> M1 i c f b) -> M1 i c f b #

(>>) :: M1 i c f a -> M1 i c f b -> M1 i c f b #

return :: a -> M1 i c f a #

data Either a b #

The Either type represents values with two possibilities: a value of type Either a b is either Left a or Right b.

The Either type is sometimes used to represent a value which is either correct or an error; by convention, the Left constructor is used to hold an error value and the Right constructor is used to hold a correct value (mnemonic: "right" also means "correct").

Examples

Expand

The type Either String Int is the type of values which can be either a String or an Int. The Left constructor can be used only on Strings, and the Right constructor can be used only on Ints:

>>> let s = Left "foo" :: Either String Int
>>> s
Left "foo"
>>> let n = Right 3 :: Either String Int
>>> n
Right 3
>>> :type s
s :: Either String Int
>>> :type n
n :: Either String Int

The fmap from our Functor instance will ignore Left values, but will apply the supplied function to values contained in a Right:

>>> let s = Left "foo" :: Either String Int
>>> let n = Right 3 :: Either String Int
>>> fmap (*2) s
Left "foo"
>>> fmap (*2) n
Right 6

The Monad instance for Either allows us to chain together multiple actions which may fail, and fail overall if any of the individual steps failed. First we'll write a function that can either parse an Int from a Char, or fail.

>>> import Data.Char ( digitToInt, isDigit )
>>> :{
    let parseEither :: Char -> Either String Int
        parseEither c
          | isDigit c = Right (digitToInt c)
          | otherwise = Left "parse error"
>>> :}

The following should work, since both '1' and '2' can be parsed as Ints.

>>> :{
    let parseMultiple :: Either String Int
        parseMultiple = do
          x <- parseEither '1'
          y <- parseEither '2'
          return (x + y)
>>> :}
>>> parseMultiple
Right 3

But the following should fail overall, since the first operation where we attempt to parse 'm' as an Int will fail:

>>> :{
    let parseMultiple :: Either String Int
        parseMultiple = do
          x <- parseEither 'm'
          y <- parseEither '2'
          return (x + y)
>>> :}
>>> parseMultiple
Left "parse error"

Constructors

Left a 
Right b 

Instances

Instances details
Generic1 (Either a :: Type -> Type) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep1 (Either a) :: k -> Type #

Methods

from1 :: forall (a0 :: k). Either a a0 -> Rep1 (Either a) a0 #

to1 :: forall (a0 :: k). Rep1 (Either a) a0 -> Either a a0 #

Foldable (Either a)

Since: base-4.7.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Either a m -> m #

foldMap :: Monoid m => (a0 -> m) -> Either a a0 -> m #

foldMap' :: Monoid m => (a0 -> m) -> Either a a0 -> m #

foldr :: (a0 -> b -> b) -> b -> Either a a0 -> b #

foldr' :: (a0 -> b -> b) -> b -> Either a a0 -> b #

foldl :: (b -> a0 -> b) -> b -> Either a a0 -> b #

foldl' :: (b -> a0 -> b) -> b -> Either a a0 -> b #

foldr1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 #

toList :: Either a a0 -> [a0] #

null :: Either a a0 -> Bool #

length :: Either a a0 -> Int #

elem :: Eq a0 => a0 -> Either a a0 -> Bool #

maximum :: Ord a0 => Either a a0 -> a0 #

minimum :: Ord a0 => Either a a0 -> a0 #

sum :: Num a0 => Either a a0 -> a0 #

product :: Num a0 => Either a a0 -> a0 #

Traversable (Either a)

Since: base-4.7.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a0 -> f b) -> Either a a0 -> f (Either a b) #

sequenceA :: Applicative f => Either a (f a0) -> f (Either a a0) #

mapM :: Monad m => (a0 -> m b) -> Either a a0 -> m (Either a b) #

sequence :: Monad m => Either a (m a0) -> m (Either a a0) #

Applicative (Either e)

Since: base-3.0

Instance details

Defined in Data.Either

Methods

pure :: a -> Either e a #

(<*>) :: Either e (a -> b) -> Either e a -> Either e b #

liftA2 :: (a -> b -> c) -> Either e a -> Either e b -> Either e c #

(*>) :: Either e a -> Either e b -> Either e b #

(<*) :: Either e a -> Either e b -> Either e a #

Functor (Either a)

Since: base-3.0

Instance details

Defined in Data.Either

Methods

fmap :: (a0 -> b) -> Either a a0 -> Either a b #

(<$) :: a0 -> Either a b -> Either a a0 #

Monad (Either e)

Since: base-4.4.0.0

Instance details

Defined in Data.Either

Methods

(>>=) :: Either e a -> (a -> Either e b) -> Either e b #

(>>) :: Either e a -> Either e b -> Either e b #

return :: a -> Either e a #

(Data a, Data b) => Data (Either a b)

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Either a b -> c (Either a b) #

gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Either a b) #

toConstr :: Either a b -> Constr #

dataTypeOf :: Either a b -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Either a b)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Either a b)) #

gmapT :: (forall b0. Data b0 => b0 -> b0) -> Either a b -> Either a b #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Either a b -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Either a b -> r #

gmapQ :: (forall d. Data d => d -> u) -> Either a b -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Either a b -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Either a b -> m (Either a b) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Either a b -> m (Either a b) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Either a b -> m (Either a b) #

Semigroup (Either a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Either

Methods

(<>) :: Either a b -> Either a b -> Either a b #

sconcat :: NonEmpty (Either a b) -> Either a b #

stimes :: Integral b0 => b0 -> Either a b -> Either a b #

Generic (Either a b) 
Instance details

Defined in GHC.Generics

Associated Types

type Rep (Either a b) :: Type -> Type #

Methods

from :: Either a b -> Rep (Either a b) x #

to :: Rep (Either a b) x -> Either a b #

(Read a, Read b) => Read (Either a b)

Since: base-3.0

Instance details

Defined in Data.Either

(Show a, Show b) => Show (Either a b)

Since: base-3.0

Instance details

Defined in Data.Either

Methods

showsPrec :: Int -> Either a b -> ShowS #

show :: Either a b -> String #

showList :: [Either a b] -> ShowS #

(Eq a, Eq b) => Eq (Either a b)

Since: base-2.1

Instance details

Defined in Data.Either

Methods

(==) :: Either a b -> Either a b -> Bool #

(/=) :: Either a b -> Either a b -> Bool #

(Ord a, Ord b) => Ord (Either a b)

Since: base-2.1

Instance details

Defined in Data.Either

Methods

compare :: Either a b -> Either a b -> Ordering #

(<) :: Either a b -> Either a b -> Bool #

(<=) :: Either a b -> Either a b -> Bool #

(>) :: Either a b -> Either a b -> Bool #

(>=) :: Either a b -> Either a b -> Bool #

max :: Either a b -> Either a b -> Either a b #

min :: Either a b -> Either a b -> Either a b #

type Rep1 (Either a :: Type -> Type)

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

type Rep (Either a b)

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

type IOError = IOException #

The Haskell 2010 type for exceptions in the IO monad. Any I/O operation may raise an IOException instead of returning a result. For a more general type of exception, including also those that arise in pure code, see Exception.

In Haskell 2010, this is an opaque type.

class Fractional a => Floating a #

Trigonometric and hyperbolic functions and related functions.

The Haskell Report defines no laws for Floating. However, (+), (*) and exp are customarily expected to define an exponential field and have the following properties:

  • exp (a + b) = exp a * exp b
  • exp (fromInteger 0) = fromInteger 1

Minimal complete definition

pi, exp, log, sin, cos, asin, acos, atan, sinh, cosh, asinh, acosh, atanh

Instances

Instances details
Floating Double

Since: base-2.1

Instance details

Defined in GHC.Float

Floating Float

Since: base-2.1

Instance details

Defined in GHC.Float

Floating a => Floating (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Floating a => Floating (Down a)

Since: base-4.14.0.0

Instance details

Defined in Data.Ord

Methods

pi :: Down a #

exp :: Down a -> Down a #

log :: Down a -> Down a #

sqrt :: Down a -> Down a #

(**) :: Down a -> Down a -> Down a #

logBase :: Down a -> Down a -> Down a #

sin :: Down a -> Down a #

cos :: Down a -> Down a #

tan :: Down a -> Down a #

asin :: Down a -> Down a #

acos :: Down a -> Down a #

atan :: Down a -> Down a #

sinh :: Down a -> Down a #

cosh :: Down a -> Down a #

tanh :: Down a -> Down a #

asinh :: Down a -> Down a #

acosh :: Down a -> Down a #

atanh :: Down a -> Down a #

log1p :: Down a -> Down a #

expm1 :: Down a -> Down a #

log1pexp :: Down a -> Down a #

log1mexp :: Down a -> Down a #

Floating a => Floating (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

pi :: Const a b #

exp :: Const a b -> Const a b #

log :: Const a b -> Const a b #

sqrt :: Const a b -> Const a b #

(**) :: Const a b -> Const a b -> Const a b #

logBase :: Const a b -> Const a b -> Const a b #

sin :: Const a b -> Const a b #

cos :: Const a b -> Const a b #

tan :: Const a b -> Const a b #

asin :: Const a b -> Const a b #

acos :: Const a b -> Const a b #

atan :: Const a b -> Const a b #

sinh :: Const a b -> Const a b #

cosh :: Const a b -> Const a b #

tanh :: Const a b -> Const a b #

asinh :: Const a b -> Const a b #

acosh :: Const a b -> Const a b #

atanh :: Const a b -> Const a b #

log1p :: Const a b -> Const a b #

expm1 :: Const a b -> Const a b #

log1pexp :: Const a b -> Const a b #

log1mexp :: Const a b -> Const a b #

class Num a #

Basic numeric class.

The Haskell Report defines no laws for Num. However, (+) and (*) are customarily expected to define a ring and have the following properties:

Associativity of (+)
(x + y) + z = x + (y + z)
Commutativity of (+)
x + y = y + x
fromInteger 0 is the additive identity
x + fromInteger 0 = x
negate gives the additive inverse
x + negate x = fromInteger 0
Associativity of (*)
(x * y) * z = x * (y * z)
fromInteger 1 is the multiplicative identity
x * fromInteger 1 = x and fromInteger 1 * x = x
Distributivity of (*) with respect to (+)
a * (b + c) = (a * b) + (a * c) and (b + c) * a = (b * a) + (c * a)
Coherence with toInteger
if the type also implements Integral, then fromInteger is a left inverse for toInteger, i.e. fromInteger (toInteger i) == i

Note that it isn't customarily expected that a type instance of both Num and Ord implement an ordered ring. Indeed, in base only Integer and Rational do.

Minimal complete definition

(+), (*), abs, signum, fromInteger, (negate | (-))

Instances

Instances details
Num Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Num Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Num Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Num Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Methods

(+) :: Int8 -> Int8 -> Int8 #

(-) :: Int8 -> Int8 -> Int8 #

(*) :: Int8 -> Int8 -> Int8 #

negate :: Int8 -> Int8 #

abs :: Int8 -> Int8 #

signum :: Int8 -> Int8 #

fromInteger :: Integer -> Int8 #

Num Word16

Since: base-2.1

Instance details

Defined in GHC.Word

Num Word32

Since: base-2.1

Instance details

Defined in GHC.Word

Num Word64

Since: base-2.1

Instance details

Defined in GHC.Word

Num Word8

Since: base-2.1

Instance details

Defined in GHC.Word

Num Integer

Since: base-2.1

Instance details

Defined in GHC.Num

Num Natural

Note that Natural's Num instance isn't a ring: no element but 0 has an additive inverse. It is a semiring though.

Since: base-4.8.0.0

Instance details

Defined in GHC.Num

Num Int

Since: base-2.1

Instance details

Defined in GHC.Num

Methods

(+) :: Int -> Int -> Int #

(-) :: Int -> Int -> Int #

(*) :: Int -> Int -> Int #

negate :: Int -> Int #

abs :: Int -> Int #

signum :: Int -> Int #

fromInteger :: Integer -> Int #

Num Word

Since: base-2.1

Instance details

Defined in GHC.Num

Methods

(+) :: Word -> Word -> Word #

(-) :: Word -> Word -> Word #

(*) :: Word -> Word -> Word #

negate :: Word -> Word #

abs :: Word -> Word #

signum :: Word -> Word #

fromInteger :: Integer -> Word #

Num a => Num (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Num a => Num (Down a)

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

(+) :: Down a -> Down a -> Down a #

(-) :: Down a -> Down a -> Down a #

(*) :: Down a -> Down a -> Down a #

negate :: Down a -> Down a #

abs :: Down a -> Down a #

signum :: Down a -> Down a #

fromInteger :: Integer -> Down a #

Num a => Num (Max a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(+) :: Max a -> Max a -> Max a #

(-) :: Max a -> Max a -> Max a #

(*) :: Max a -> Max a -> Max a #

negate :: Max a -> Max a #

abs :: Max a -> Max a #

signum :: Max a -> Max a #

fromInteger :: Integer -> Max a #

Num a => Num (Min a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

(+) :: Min a -> Min a -> Min a #

(-) :: Min a -> Min a -> Min a #

(*) :: Min a -> Min a -> Min a #

negate :: Min a -> Min a #

abs :: Min a -> Min a #

signum :: Min a -> Min a #

fromInteger :: Integer -> Min a #

Num a => Num (Product a)

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(+) :: Product a -> Product a -> Product a #

(-) :: Product a -> Product a -> Product a #

(*) :: Product a -> Product a -> Product a #

negate :: Product a -> Product a #

abs :: Product a -> Product a #

signum :: Product a -> Product a #

fromInteger :: Integer -> Product a #

Num a => Num (Sum a)

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(+) :: Sum a -> Sum a -> Sum a #

(-) :: Sum a -> Sum a -> Sum a #

(*) :: Sum a -> Sum a -> Sum a #

negate :: Sum a -> Sum a #

abs :: Sum a -> Sum a #

signum :: Sum a -> Sum a #

fromInteger :: Integer -> Sum a #

Integral a => Num (Ratio a)

Since: base-2.0.1

Instance details

Defined in GHC.Real

Methods

(+) :: Ratio a -> Ratio a -> Ratio a #

(-) :: Ratio a -> Ratio a -> Ratio a #

(*) :: Ratio a -> Ratio a -> Ratio a #

negate :: Ratio a -> Ratio a #

abs :: Ratio a -> Ratio a #

signum :: Ratio a -> Ratio a #

fromInteger :: Integer -> Ratio a #

Num a => Num (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

(+) :: Const a b -> Const a b -> Const a b #

(-) :: Const a b -> Const a b -> Const a b #

(*) :: Const a b -> Const a b -> Const a b #

negate :: Const a b -> Const a b #

abs :: Const a b -> Const a b #

signum :: Const a b -> Const a b #

fromInteger :: Integer -> Const a b #

(Applicative f, Num a) => Num (Ap f a)

Note that even if the underlying Num and Applicative instances are lawful, for most Applicatives, this instance will not be lawful. If you use this instance with the list Applicative, the following customary laws will not hold:

Commutativity:

>>> Ap [10,20] + Ap [1,2]
Ap {getAp = [11,12,21,22]}
>>> Ap [1,2] + Ap [10,20]
Ap {getAp = [11,21,12,22]}

Additive inverse:

>>> Ap [] + negate (Ap [])
Ap {getAp = []}
>>> fromInteger 0 :: Ap [] Int
Ap {getAp = [0]}

Distributivity:

>>> Ap [1,2] * (3 + 4)
Ap {getAp = [7,14]}
>>> (Ap [1,2] * 3) + (Ap [1,2] * 4)
Ap {getAp = [7,11,10,14]}

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

(+) :: Ap f a -> Ap f a -> Ap f a #

(-) :: Ap f a -> Ap f a -> Ap f a #

(*) :: Ap f a -> Ap f a -> Ap f a #

negate :: Ap f a -> Ap f a #

abs :: Ap f a -> Ap f a #

signum :: Ap f a -> Ap f a #

fromInteger :: Integer -> Ap f a #

Num (f a) => Num (Alt f a)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(+) :: Alt f a -> Alt f a -> Alt f a #

(-) :: Alt f a -> Alt f a -> Alt f a #

(*) :: Alt f a -> Alt f a -> Alt f a #

negate :: Alt f a -> Alt f a #

abs :: Alt f a -> Alt f a #

signum :: Alt f a -> Alt f a #

fromInteger :: Integer -> Alt f a #

class (RealFrac a, Floating a) => RealFloat a where #

Efficient, machine-independent access to the components of a floating-point number.

Methods

floatRadix :: a -> Integer #

a constant function, returning the radix of the representation (often 2)

floatDigits :: a -> Int #

a constant function, returning the number of digits of floatRadix in the significand

floatRange :: a -> (Int, Int) #

a constant function, returning the lowest and highest values the exponent may assume

decodeFloat :: a -> (Integer, Int) #

The function decodeFloat applied to a real floating-point number returns the significand expressed as an Integer and an appropriately scaled exponent (an Int). If decodeFloat x yields (m,n), then x is equal in value to m*b^^n, where b is the floating-point radix, and furthermore, either m and n are both zero or else b^(d-1) <= abs m < b^d, where d is the value of floatDigits x. In particular, decodeFloat 0 = (0,0). If the type contains a negative zero, also decodeFloat (-0.0) = (0,0). The result of decodeFloat x is unspecified if either of isNaN x or isInfinite x is True.

encodeFloat :: Integer -> Int -> a #

encodeFloat performs the inverse of decodeFloat in the sense that for finite x with the exception of -0.0, uncurry encodeFloat (decodeFloat x) = x. encodeFloat m n is one of the two closest representable floating-point numbers to m*b^^n (or ±Infinity if overflow occurs); usually the closer, but if m contains too many bits, the result may be rounded in the wrong direction.

exponent :: a -> Int #

exponent corresponds to the second component of decodeFloat. exponent 0 = 0 and for finite nonzero x, exponent x = snd (decodeFloat x) + floatDigits x. If x is a finite floating-point number, it is equal in value to significand x * b ^^ exponent x, where b is the floating-point radix. The behaviour is unspecified on infinite or NaN values.

significand :: a -> a #

The first component of decodeFloat, scaled to lie in the open interval (-1,1), either 0.0 or of absolute value >= 1/b, where b is the floating-point radix. The behaviour is unspecified on infinite or NaN values.

scaleFloat :: Int -> a -> a #

multiplies a floating-point number by an integer power of the radix

isNaN :: a -> Bool #

True if the argument is an IEEE "not-a-number" (NaN) value

isInfinite :: a -> Bool #

True if the argument is an IEEE infinity or negative infinity

isDenormalized :: a -> Bool #

True if the argument is too small to be represented in normalized format

isNegativeZero :: a -> Bool #

True if the argument is an IEEE negative zero

isIEEE :: a -> Bool #

True if the argument is an IEEE floating point number

Instances

Instances details
RealFloat Double

Since: base-2.1

Instance details

Defined in GHC.Float

RealFloat Float

Since: base-2.1

Instance details

Defined in GHC.Float

RealFloat a => RealFloat (Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

RealFloat a => RealFloat (Down a)

Since: base-4.14.0.0

Instance details

Defined in Data.Ord

RealFloat a => RealFloat (Const a b)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

floatRadix :: Const a b -> Integer #

floatDigits :: Const a b -> Int #

floatRange :: Const a b -> (Int, Int) #

decodeFloat :: Const a b -> (Integer, Int) #

encodeFloat :: Integer -> Int -> Const a b #

exponent :: Const a b -> Int #

significand :: Const a b -> Const a b #

scaleFloat :: Int -> Const a b -> Const a b #

isNaN :: Const a b -> Bool #

isInfinite :: Const a b -> Bool #

isDenormalized :: Const a b -> Bool #

isNegativeZero :: Const a b -> Bool #

isIEEE :: Const a b -> Bool #

atan2 :: Const a b -> Const a b -> Const a b #

class Monad m => MonadFail (m :: Type -> Type) where #

When a value is bound in do-notation, the pattern on the left hand side of <- might not match. In this case, this class provides a function to recover.

A Monad without a MonadFail instance may only be used in conjunction with pattern that always match, such as newtypes, tuples, data types with only a single data constructor, and irrefutable patterns (~pat).

Instances of MonadFail should satisfy the following law: fail s should be a left zero for >>=,

fail s >>= f  =  fail s

If your Monad is also MonadPlus, a popular definition is

fail _ = mzero

fail s should be an action that runs in the monad itself, not an exception (except in instances of MonadIO). In particular, fail should not be implemented in terms of error.

Since: base-4.9.0.0

Methods

fail :: String -> m a #

Instances

Instances details
MonadFail P

Since: base-4.9.0.0

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

fail :: String -> P a #

MonadFail ReadP

Since: base-4.9.0.0

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

fail :: String -> ReadP a #

MonadFail ReadPrec

Since: base-4.9.0.0

Instance details

Defined in Text.ParserCombinators.ReadPrec

Methods

fail :: String -> ReadPrec a #

MonadFail IO

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fail

Methods

fail :: String -> IO a #

MonadFail Maybe

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fail

Methods

fail :: String -> Maybe a #

MonadFail List

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fail

Methods

fail :: String -> [a] #

MonadFail f => MonadFail (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

fail :: String -> Ap f a #

class Foldable (t :: Type -> Type) where #

The Foldable class represents data structures that can be reduced to a summary value one element at a time. Strict left-associative folds are a good fit for space-efficient reduction, while lazy right-associative folds are a good fit for corecursive iteration, or for folds that short-circuit after processing an initial subsequence of the structure's elements.

Instances can be derived automatically by enabling the DeriveFoldable extension. For example, a derived instance for a binary tree might be:

{-# LANGUAGE DeriveFoldable #-}
data Tree a = Empty
            | Leaf a
            | Node (Tree a) a (Tree a)
    deriving Foldable

A more detailed description can be found in the Overview section of Data.Foldable.

For the class laws see the Laws section of Data.Foldable.

Minimal complete definition

foldMap | foldr

Methods

foldMap :: Monoid m => (a -> m) -> t a -> m #

Map each element of the structure into a monoid, and combine the results with (<>). This fold is right-associative and lazy in the accumulator. For strict left-associative folds consider foldMap' instead.

Examples

Expand

Basic usage:

>>> foldMap Sum [1, 3, 5]
Sum {getSum = 9}
>>> foldMap Product [1, 3, 5]
Product {getProduct = 15}
>>> foldMap (replicate 3) [1, 2, 3]
[1,1,1,2,2,2,3,3,3]

When a Monoid's (<>) is lazy in its second argument, foldMap can return a result even from an unbounded structure. For example, lazy accumulation enables Data.ByteString.Builder to efficiently serialise large data structures and produce the output incrementally:

>>> import qualified Data.ByteString.Lazy as L
>>> import qualified Data.ByteString.Builder as B
>>> let bld :: Int -> B.Builder; bld i = B.intDec i <> B.word8 0x20
>>> let lbs = B.toLazyByteString $ foldMap bld [0..]
>>> L.take 64 lbs
"0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24"

foldr :: (a -> b -> b) -> b -> t a -> b #

Right-associative fold of a structure, lazy in the accumulator.

In the case of lists, foldr, when applied to a binary operator, a starting value (typically the right-identity of the operator), and a list, reduces the list using the binary operator, from right to left:

foldr f z [x1, x2, ..., xn] == x1 `f` (x2 `f` ... (xn `f` z)...)

Note that since the head of the resulting expression is produced by an application of the operator to the first element of the list, given an operator lazy in its right argument, foldr can produce a terminating expression from an unbounded list.

For a general Foldable structure this should be semantically identical to,

foldr f z = foldr f z . toList

Examples

Expand

Basic usage:

>>> foldr (||) False [False, True, False]
True
>>> foldr (||) False []
False
>>> foldr (\c acc -> acc ++ [c]) "foo" ['a', 'b', 'c', 'd']
"foodcba"
Infinite structures

⚠️ Applying foldr to infinite structures usually doesn't terminate.

It may still terminate under one of the following conditions:

  • the folding function is short-circuiting
  • the folding function is lazy on its second argument
Short-circuiting

(||) short-circuits on True values, so the following terminates because there is a True value finitely far from the left side:

>>> foldr (||) False (True : repeat False)
True

But the following doesn't terminate:

>>> foldr (||) False (repeat False ++ [True])
* Hangs forever *
Laziness in the second argument

Applying foldr to infinite structures terminates when the operator is lazy in its second argument (the initial accumulator is never used in this case, and so could be left undefined, but [] is more clear):

>>> take 5 $ foldr (\i acc -> i : fmap (+3) acc) [] (repeat 1)
[1,4,7,10,13]

foldl :: (b -> a -> b) -> b -> t a -> b #

Left-associative fold of a structure, lazy in the accumulator. This is rarely what you want, but can work well for structures with efficient right-to-left sequencing and an operator that is lazy in its left argument.

In the case of lists, foldl, when applied to a binary operator, a starting value (typically the left-identity of the operator), and a list, reduces the list using the binary operator, from left to right:

foldl f z [x1, x2, ..., xn] == (...((z `f` x1) `f` x2) `f`...) `f` xn

Note that to produce the outermost application of the operator the entire input list must be traversed. Like all left-associative folds, foldl will diverge if given an infinite list.

If you want an efficient strict left-fold, you probably want to use foldl' instead of foldl. The reason for this is that the latter does not force the inner results (e.g. z `f` x1 in the above example) before applying them to the operator (e.g. to (`f` x2)). This results in a thunk chain O(n) elements long, which then must be evaluated from the outside-in.

For a general Foldable structure this should be semantically identical to:

foldl f z = foldl f z . toList

Examples

Expand

The first example is a strict fold, which in practice is best performed with foldl'.

>>> foldl (+) 42 [1,2,3,4]
52

Though the result below is lazy, the input is reversed before prepending it to the initial accumulator, so corecursion begins only after traversing the entire input string.

>>> foldl (\acc c -> c : acc) "abcd" "efgh"
"hgfeabcd"

A left fold of a structure that is infinite on the right cannot terminate, even when for any finite input the fold just returns the initial accumulator:

>>> foldl (\a _ -> a) 0 $ repeat 1
* Hangs forever *

WARNING: When it comes to lists, you always want to use either foldl' or foldr instead.

foldr1 :: (a -> a -> a) -> t a -> a #

A variant of foldr that has no base case, and thus may only be applied to non-empty structures.

This function is non-total and will raise a runtime exception if the structure happens to be empty.

Examples

Expand

Basic usage:

>>> foldr1 (+) [1..4]
10
>>> foldr1 (+) []
Exception: Prelude.foldr1: empty list
>>> foldr1 (+) Nothing
*** Exception: foldr1: empty structure
>>> foldr1 (-) [1..4]
-2
>>> foldr1 (&&) [True, False, True, True]
False
>>> foldr1 (||) [False, False, True, True]
True
>>> foldr1 (+) [1..]
* Hangs forever *

foldl1 :: (a -> a -> a) -> t a -> a #

A variant of foldl that has no base case, and thus may only be applied to non-empty structures.

This function is non-total and will raise a runtime exception if the structure happens to be empty.

foldl1 f = foldl1 f . toList

Examples

Expand

Basic usage:

>>> foldl1 (+) [1..4]
10
>>> foldl1 (+) []
*** Exception: Prelude.foldl1: empty list
>>> foldl1 (+) Nothing
*** Exception: foldl1: empty structure
>>> foldl1 (-) [1..4]
-8
>>> foldl1 (&&) [True, False, True, True]
False
>>> foldl1 (||) [False, False, True, True]
True
>>> foldl1 (+) [1..]
* Hangs forever *

null :: t a -> Bool #

Test whether the structure is empty. The default implementation is Left-associative and lazy in both the initial element and the accumulator. Thus optimised for structures where the first element can be accessed in constant time. Structures where this is not the case should have a non-default implementation.

Examples

Expand

Basic usage:

>>> null []
True
>>> null [1]
False

null is expected to terminate even for infinite structures. The default implementation terminates provided the structure is bounded on the left (there is a leftmost element).

>>> null [1..]
False

Since: base-4.8.0.0

length :: t a -> Int #

Returns the size/length of a finite structure as an Int. The default implementation just counts elements starting with the leftmost. Instances for structures that can compute the element count faster than via element-by-element counting, should provide a specialised implementation.

Examples

Expand

Basic usage:

>>> length []
0
>>> length ['a', 'b', 'c']
3
>>> length [1..]
* Hangs forever *

Since: base-4.8.0.0

elem :: Eq a => a -> t a -> Bool infix 4 #

Does the element occur in the structure?

Note: elem is often used in infix form.

Examples

Expand

Basic usage:

>>> 3 `elem` []
False
>>> 3 `elem` [1,2]
False
>>> 3 `elem` [1,2,3,4,5]
True

For infinite structures, the default implementation of elem terminates if the sought-after value exists at a finite distance from the left side of the structure:

>>> 3 `elem` [1..]
True
>>> 3 `elem` ([4..] ++ [3])
* Hangs forever *

Since: base-4.8.0.0

maximum :: Ord a => t a -> a #

The largest element of a non-empty structure.

This function is non-total and will raise a runtime exception if the structure happens to be empty. A structure that supports random access and maintains its elements in order should provide a specialised implementation to return the maximum in faster than linear time.

Examples

Expand

Basic usage:

>>> maximum [1..10]
10
>>> maximum []
*** Exception: Prelude.maximum: empty list
>>> maximum Nothing
*** Exception: maximum: empty structure

WARNING: This function is partial for possibly-empty structures like lists.

Since: base-4.8.0.0

minimum :: Ord a => t a -> a #

The least element of a non-empty structure.

This function is non-total and will raise a runtime exception if the structure happens to be empty. A structure that supports random access and maintains its elements in order should provide a specialised implementation to return the minimum in faster than linear time.

Examples

Expand

Basic usage:

>>> minimum [1..10]
1
>>> minimum []
*** Exception: Prelude.minimum: empty list
>>> minimum Nothing
*** Exception: minimum: empty structure

WARNING: This function is partial for possibly-empty structures like lists.

Since: base-4.8.0.0

Instances

Instances details
Foldable ZipList

Since: base-4.9.0.0

Instance details

Defined in Control.Applicative

Methods

fold :: Monoid m => ZipList m -> m #

foldMap :: Monoid m => (a -> m) -> ZipList a -> m #

foldMap' :: Monoid m => (a -> m) -> ZipList a -> m #

foldr :: (a -> b -> b) -> b -> ZipList a -> b #

foldr' :: (a -> b -> b) -> b -> ZipList a -> b #

foldl :: (b -> a -> b) -> b -> ZipList a -> b #

foldl' :: (b -> a -> b) -> b -> ZipList a -> b #

foldr1 :: (a -> a -> a) -> ZipList a -> a #

foldl1 :: (a -> a -> a) -> ZipList a -> a #

toList :: ZipList a -> [a] #

null :: ZipList a -> Bool #

length :: ZipList a -> Int #

elem :: Eq a => a -> ZipList a -> Bool #

maximum :: Ord a => ZipList a -> a #

minimum :: Ord a => ZipList a -> a #

sum :: Num a => ZipList a -> a #

product :: Num a => ZipList a -> a #

Foldable Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

fold :: Monoid m => Identity m -> m #

foldMap :: Monoid m => (a -> m) -> Identity a -> m #

foldMap' :: Monoid m => (a -> m) -> Identity a -> m #

foldr :: (a -> b -> b) -> b -> Identity a -> b #

foldr' :: (a -> b -> b) -> b -> Identity a -> b #

foldl :: (b -> a -> b) -> b -> Identity a -> b #

foldl' :: (b -> a -> b) -> b -> Identity a -> b #

foldr1 :: (a -> a -> a) -> Identity a -> a #

foldl1 :: (a -> a -> a) -> Identity a -> a #

toList :: Identity a -> [a] #

null :: Identity a -> Bool #

length :: Identity a -> Int #

elem :: Eq a => a -> Identity a -> Bool #

maximum :: Ord a => Identity a -> a #

minimum :: Ord a => Identity a -> a #

sum :: Num a => Identity a -> a #

product :: Num a => Identity a -> a #

Foldable First

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => First m -> m #

foldMap :: Monoid m => (a -> m) -> First a -> m #

foldMap' :: Monoid m => (a -> m) -> First a -> m #

foldr :: (a -> b -> b) -> b -> First a -> b #

foldr' :: (a -> b -> b) -> b -> First a -> b #

foldl :: (b -> a -> b) -> b -> First a -> b #

foldl' :: (b -> a -> b) -> b -> First a -> b #

foldr1 :: (a -> a -> a) -> First a -> a #

foldl1 :: (a -> a -> a) -> First a -> a #

toList :: First a -> [a] #

null :: First a -> Bool #

length :: First a -> Int #

elem :: Eq a => a -> First a -> Bool #

maximum :: Ord a => First a -> a #

minimum :: Ord a => First a -> a #

sum :: Num a => First a -> a #

product :: Num a => First a -> a #

Foldable Last

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Last m -> m #

foldMap :: Monoid m => (a -> m) -> Last a -> m #

foldMap' :: Monoid m => (a -> m) -> Last a -> m #

foldr :: (a -> b -> b) -> b -> Last a -> b #

foldr' :: (a -> b -> b) -> b -> Last a -> b #

foldl :: (b -> a -> b) -> b -> Last a -> b #

foldl' :: (b -> a -> b) -> b -> Last a -> b #

foldr1 :: (a -> a -> a) -> Last a -> a #

foldl1 :: (a -> a -> a) -> Last a -> a #

toList :: Last a -> [a] #

null :: Last a -> Bool #

length :: Last a -> Int #

elem :: Eq a => a -> Last a -> Bool #

maximum :: Ord a => Last a -> a #

minimum :: Ord a => Last a -> a #

sum :: Num a => Last a -> a #

product :: Num a => Last a -> a #

Foldable Down

Since: base-4.12.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Down m -> m #

foldMap :: Monoid m => (a -> m) -> Down a -> m #

foldMap' :: Monoid m => (a -> m) -> Down a -> m #

foldr :: (a -> b -> b) -> b -> Down a -> b #

foldr' :: (a -> b -> b) -> b -> Down a -> b #

foldl :: (b -> a -> b) -> b -> Down a -> b #

foldl' :: (b -> a -> b) -> b -> Down a -> b #

foldr1 :: (a -> a -> a) -> Down a -> a #

foldl1 :: (a -> a -> a) -> Down a -> a #

toList :: Down a -> [a] #

null :: Down a -> Bool #

length :: Down a -> Int #

elem :: Eq a => a -> Down a -> Bool #

maximum :: Ord a => Down a -> a #

minimum :: Ord a => Down a -> a #

sum :: Num a => Down a -> a #

product :: Num a => Down a -> a #

Foldable First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => First m -> m #

foldMap :: Monoid m => (a -> m) -> First a -> m #

foldMap' :: Monoid m => (a -> m) -> First a -> m #

foldr :: (a -> b -> b) -> b -> First a -> b #

foldr' :: (a -> b -> b) -> b -> First a -> b #

foldl :: (b -> a -> b) -> b -> First a -> b #

foldl' :: (b -> a -> b) -> b -> First a -> b #

foldr1 :: (a -> a -> a) -> First a -> a #

foldl1 :: (a -> a -> a) -> First a -> a #

toList :: First a -> [a] #

null :: First a -> Bool #

length :: First a -> Int #

elem :: Eq a => a -> First a -> Bool #

maximum :: Ord a => First a -> a #

minimum :: Ord a => First a -> a #

sum :: Num a => First a -> a #

product :: Num a => First a -> a #

Foldable Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Last m -> m #

foldMap :: Monoid m => (a -> m) -> Last a -> m #

foldMap' :: Monoid m => (a -> m) -> Last a -> m #

foldr :: (a -> b -> b) -> b -> Last a -> b #

foldr' :: (a -> b -> b) -> b -> Last a -> b #

foldl :: (b -> a -> b) -> b -> Last a -> b #

foldl' :: (b -> a -> b) -> b -> Last a -> b #

foldr1 :: (a -> a -> a) -> Last a -> a #

foldl1 :: (a -> a -> a) -> Last a -> a #

toList :: Last a -> [a] #

null :: Last a -> Bool #

length :: Last a -> Int #

elem :: Eq a => a -> Last a -> Bool #

maximum :: Ord a => Last a -> a #

minimum :: Ord a => Last a -> a #

sum :: Num a => Last a -> a #

product :: Num a => Last a -> a #

Foldable Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Max m -> m #

foldMap :: Monoid m => (a -> m) -> Max a -> m #

foldMap' :: Monoid m => (a -> m) -> Max a -> m #

foldr :: (a -> b -> b) -> b -> Max a -> b #

foldr' :: (a -> b -> b) -> b -> Max a -> b #

foldl :: (b -> a -> b) -> b -> Max a -> b #

foldl' :: (b -> a -> b) -> b -> Max a -> b #

foldr1 :: (a -> a -> a) -> Max a -> a #

foldl1 :: (a -> a -> a) -> Max a -> a #

toList :: Max a -> [a] #

null :: Max a -> Bool #

length :: Max a -> Int #

elem :: Eq a => a -> Max a -> Bool #

maximum :: Ord a => Max a -> a #

minimum :: Ord a => Max a -> a #

sum :: Num a => Max a -> a #

product :: Num a => Max a -> a #

Foldable Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Min m -> m #

foldMap :: Monoid m => (a -> m) -> Min a -> m #

foldMap' :: Monoid m => (a -> m) -> Min a -> m #

foldr :: (a -> b -> b) -> b -> Min a -> b #

foldr' :: (a -> b -> b) -> b -> Min a -> b #

foldl :: (b -> a -> b) -> b -> Min a -> b #

foldl' :: (b -> a -> b) -> b -> Min a -> b #

foldr1 :: (a -> a -> a) -> Min a -> a #

foldl1 :: (a -> a -> a) -> Min a -> a #

toList :: Min a -> [a] #

null :: Min a -> Bool #

length :: Min a -> Int #

elem :: Eq a => a -> Min a -> Bool #

maximum :: Ord a => Min a -> a #

minimum :: Ord a => Min a -> a #

sum :: Num a => Min a -> a #

product :: Num a => Min a -> a #

Foldable Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Dual m -> m #

foldMap :: Monoid m => (a -> m) -> Dual a -> m #

foldMap' :: Monoid m => (a -> m) -> Dual a -> m #

foldr :: (a -> b -> b) -> b -> Dual a -> b #

foldr' :: (a -> b -> b) -> b -> Dual a -> b #

foldl :: (b -> a -> b) -> b -> Dual a -> b #

foldl' :: (b -> a -> b) -> b -> Dual a -> b #

foldr1 :: (a -> a -> a) -> Dual a -> a #

foldl1 :: (a -> a -> a) -> Dual a -> a #

toList :: Dual a -> [a] #

null :: Dual a -> Bool #

length :: Dual a -> Int #

elem :: Eq a => a -> Dual a -> Bool #

maximum :: Ord a => Dual a -> a #

minimum :: Ord a => Dual a -> a #

sum :: Num a => Dual a -> a #

product :: Num a => Dual a -> a #

Foldable Product

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Product m -> m #

foldMap :: Monoid m => (a -> m) -> Product a -> m #

foldMap' :: Monoid m => (a -> m) -> Product a -> m #

foldr :: (a -> b -> b) -> b -> Product a -> b #

foldr' :: (a -> b -> b) -> b -> Product a -> b #

foldl :: (b -> a -> b) -> b -> Product a -> b #

foldl' :: (b -> a -> b) -> b -> Product a -> b #

foldr1 :: (a -> a -> a) -> Product a -> a #

foldl1 :: (a -> a -> a) -> Product a -> a #

toList :: Product a -> [a] #

null :: Product a -> Bool #

length :: Product a -> Int #

elem :: Eq a => a -> Product a -> Bool #

maximum :: Ord a => Product a -> a #

minimum :: Ord a => Product a -> a #

sum :: Num a => Product a -> a #

product :: Num a => Product a -> a #

Foldable Sum

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Sum m -> m #

foldMap :: Monoid m => (a -> m) -> Sum a -> m #

foldMap' :: Monoid m => (a -> m) -> Sum a -> m #

foldr :: (a -> b -> b) -> b -> Sum a -> b #

foldr' :: (a -> b -> b) -> b -> Sum a -> b #

foldl :: (b -> a -> b) -> b -> Sum a -> b #

foldl' :: (b -> a -> b) -> b -> Sum a -> b #

foldr1 :: (a -> a -> a) -> Sum a -> a #

foldl1 :: (a -> a -> a) -> Sum a -> a #

toList :: Sum a -> [a] #

null :: Sum a -> Bool #

length :: Sum a -> Int #

elem :: Eq a => a -> Sum a -> Bool #

maximum :: Ord a => Sum a -> a #

minimum :: Ord a => Sum a -> a #

sum :: Num a => Sum a -> a #

product :: Num a => Sum a -> a #

Foldable NonEmpty

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => NonEmpty m -> m #

foldMap :: Monoid m => (a -> m) -> NonEmpty a -> m #

foldMap' :: Monoid m => (a -> m) -> NonEmpty a -> m #

foldr :: (a -> b -> b) -> b -> NonEmpty a -> b #

foldr' :: (a -> b -> b) -> b -> NonEmpty a -> b #

foldl :: (b -> a -> b) -> b -> NonEmpty a -> b #

foldl' :: (b -> a -> b) -> b -> NonEmpty a -> b #

foldr1 :: (a -> a -> a) -> NonEmpty a -> a #

foldl1 :: (a -> a -> a) -> NonEmpty a -> a #

toList :: NonEmpty a -> [a] #

null :: NonEmpty a -> Bool #

length :: NonEmpty a -> Int #

elem :: Eq a => a -> NonEmpty a -> Bool #

maximum :: Ord a => NonEmpty a -> a #

minimum :: Ord a => NonEmpty a -> a #

sum :: Num a => NonEmpty a -> a #

product :: Num a => NonEmpty a -> a #

Foldable Par1

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Par1 m -> m #

foldMap :: Monoid m => (a -> m) -> Par1 a -> m #

foldMap' :: Monoid m => (a -> m) -> Par1 a -> m #

foldr :: (a -> b -> b) -> b -> Par1 a -> b #

foldr' :: (a -> b -> b) -> b -> Par1 a -> b #

foldl :: (b -> a -> b) -> b -> Par1 a -> b #

foldl' :: (b -> a -> b) -> b -> Par1 a -> b #

foldr1 :: (a -> a -> a) -> Par1 a -> a #

foldl1 :: (a -> a -> a) -> Par1 a -> a #

toList :: Par1 a -> [a] #

null :: Par1 a -> Bool #

length :: Par1 a -> Int #

elem :: Eq a => a -> Par1 a -> Bool #

maximum :: Ord a => Par1 a -> a #

minimum :: Ord a => Par1 a -> a #

sum :: Num a => Par1 a -> a #

product :: Num a => Par1 a -> a #

Foldable Maybe

Since: base-2.1

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Maybe m -> m #

foldMap :: Monoid m => (a -> m) -> Maybe a -> m #

foldMap' :: Monoid m => (a -> m) -> Maybe a -> m #

foldr :: (a -> b -> b) -> b -> Maybe a -> b #

foldr' :: (a -> b -> b) -> b -> Maybe a -> b #

foldl :: (b -> a -> b) -> b -> Maybe a -> b #

foldl' :: (b -> a -> b) -> b -> Maybe a -> b #

foldr1 :: (a -> a -> a) -> Maybe a -> a #

foldl1 :: (a -> a -> a) -> Maybe a -> a #

toList :: Maybe a -> [a] #

null :: Maybe a -> Bool #

length :: Maybe a -> Int #

elem :: Eq a => a -> Maybe a -> Bool #

maximum :: Ord a => Maybe a -> a #

minimum :: Ord a => Maybe a -> a #

sum :: Num a => Maybe a -> a #

product :: Num a => Maybe a -> a #

Foldable Solo

Since: base-4.15

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Solo m -> m #

foldMap :: Monoid m => (a -> m) -> Solo a -> m #

foldMap' :: Monoid m => (a -> m) -> Solo a -> m #

foldr :: (a -> b -> b) -> b -> Solo a -> b #

foldr' :: (a -> b -> b) -> b -> Solo a -> b #

foldl :: (b -> a -> b) -> b -> Solo a -> b #

foldl' :: (b -> a -> b) -> b -> Solo a -> b #

foldr1 :: (a -> a -> a) -> Solo a -> a #

foldl1 :: (a -> a -> a) -> Solo a -> a #

toList :: Solo a -> [a] #

null :: Solo a -> Bool #

length :: Solo a -> Int #

elem :: Eq a => a -> Solo a -> Bool #

maximum :: Ord a => Solo a -> a #

minimum :: Ord a => Solo a -> a #

sum :: Num a => Solo a -> a #

product :: Num a => Solo a -> a #

Foldable List

Since: base-2.1

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => [m] -> m #

foldMap :: Monoid m => (a -> m) -> [a] -> m #

foldMap' :: Monoid m => (a -> m) -> [a] -> m #

foldr :: (a -> b -> b) -> b -> [a] -> b #

foldr' :: (a -> b -> b) -> b -> [a] -> b #

foldl :: (b -> a -> b) -> b -> [a] -> b #

foldl' :: (b -> a -> b) -> b -> [a] -> b #

foldr1 :: (a -> a -> a) -> [a] -> a #

foldl1 :: (a -> a -> a) -> [a] -> a #

toList :: [a] -> [a] #

null :: [a] -> Bool #

length :: [a] -> Int #

elem :: Eq a => a -> [a] -> Bool #

maximum :: Ord a => [a] -> a #

minimum :: Ord a => [a] -> a #

sum :: Num a => [a] -> a #

product :: Num a => [a] -> a #

Foldable (Either a)

Since: base-4.7.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Either a m -> m #

foldMap :: Monoid m => (a0 -> m) -> Either a a0 -> m #

foldMap' :: Monoid m => (a0 -> m) -> Either a a0 -> m #

foldr :: (a0 -> b -> b) -> b -> Either a a0 -> b #

foldr' :: (a0 -> b -> b) -> b -> Either a a0 -> b #

foldl :: (b -> a0 -> b) -> b -> Either a a0 -> b #

foldl' :: (b -> a0 -> b) -> b -> Either a a0 -> b #

foldr1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 #

toList :: Either a a0 -> [a0] #

null :: Either a a0 -> Bool #

length :: Either a a0 -> Int #

elem :: Eq a0 => a0 -> Either a a0 -> Bool #

maximum :: Ord a0 => Either a a0 -> a0 #

minimum :: Ord a0 => Either a a0 -> a0 #

sum :: Num a0 => Either a a0 -> a0 #

product :: Num a0 => Either a a0 -> a0 #

Foldable (Proxy :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Proxy m -> m #

foldMap :: Monoid m => (a -> m) -> Proxy a -> m #

foldMap' :: Monoid m => (a -> m) -> Proxy a -> m #

foldr :: (a -> b -> b) -> b -> Proxy a -> b #

foldr' :: (a -> b -> b) -> b -> Proxy a -> b #

foldl :: (b -> a -> b) -> b -> Proxy a -> b #

foldl' :: (b -> a -> b) -> b -> Proxy a -> b #

foldr1 :: (a -> a -> a) -> Proxy a -> a #

foldl1 :: (a -> a -> a) -> Proxy a -> a #

toList :: Proxy a -> [a] #

null :: Proxy a -> Bool #

length :: Proxy a -> Int #

elem :: Eq a => a -> Proxy a -> Bool #

maximum :: Ord a => Proxy a -> a #

minimum :: Ord a => Proxy a -> a #

sum :: Num a => Proxy a -> a #

product :: Num a => Proxy a -> a #

Foldable (Arg a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

fold :: Monoid m => Arg a m -> m #

foldMap :: Monoid m => (a0 -> m) -> Arg a a0 -> m #

foldMap' :: Monoid m => (a0 -> m) -> Arg a a0 -> m #

foldr :: (a0 -> b -> b) -> b -> Arg a a0 -> b #

foldr' :: (a0 -> b -> b) -> b -> Arg a a0 -> b #

foldl :: (b -> a0 -> b) -> b -> Arg a a0 -> b #

foldl' :: (b -> a0 -> b) -> b -> Arg a a0 -> b #

foldr1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 #

toList :: Arg a a0 -> [a0] #

null :: Arg a a0 -> Bool #

length :: Arg a a0 -> Int #

elem :: Eq a0 => a0 -> Arg a a0 -> Bool #

maximum :: Ord a0 => Arg a a0 -> a0 #

minimum :: Ord a0 => Arg a a0 -> a0 #

sum :: Num a0 => Arg a a0 -> a0 #

product :: Num a0 => Arg a a0 -> a0 #

Foldable (Array i)

Since: base-4.8.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Array i m -> m #

foldMap :: Monoid m => (a -> m) -> Array i a -> m #

foldMap' :: Monoid m => (a -> m) -> Array i a -> m #

foldr :: (a -> b -> b) -> b -> Array i a -> b #

foldr' :: (a -> b -> b) -> b -> Array i a -> b #

foldl :: (b -> a -> b) -> b -> Array i a -> b #

foldl' :: (b -> a -> b) -> b -> Array i a -> b #

foldr1 :: (a -> a -> a) -> Array i a -> a #

foldl1 :: (a -> a -> a) -> Array i a -> a #

toList :: Array i a -> [a] #

null :: Array i a -> Bool #

length :: Array i a -> Int #

elem :: Eq a => a -> Array i a -> Bool #

maximum :: Ord a => Array i a -> a #

minimum :: Ord a => Array i a -> a #

sum :: Num a => Array i a -> a #

product :: Num a => Array i a -> a #

Foldable (U1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => U1 m -> m #

foldMap :: Monoid m => (a -> m) -> U1 a -> m #

foldMap' :: Monoid m => (a -> m) -> U1 a -> m #

foldr :: (a -> b -> b) -> b -> U1 a -> b #

foldr' :: (a -> b -> b) -> b -> U1 a -> b #

foldl :: (b -> a -> b) -> b -> U1 a -> b #

foldl' :: (b -> a -> b) -> b -> U1 a -> b #

foldr1 :: (a -> a -> a) -> U1 a -> a #

foldl1 :: (a -> a -> a) -> U1 a -> a #

toList :: U1 a -> [a] #

null :: U1 a -> Bool #

length :: U1 a -> Int #

elem :: Eq a => a -> U1 a -> Bool #

maximum :: Ord a => U1 a -> a #

minimum :: Ord a => U1 a -> a #

sum :: Num a => U1 a -> a #

product :: Num a => U1 a -> a #

Foldable (UAddr :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UAddr m -> m #

foldMap :: Monoid m => (a -> m) -> UAddr a -> m #

foldMap' :: Monoid m => (a -> m) -> UAddr a -> m #

foldr :: (a -> b -> b) -> b -> UAddr a -> b #

foldr' :: (a -> b -> b) -> b -> UAddr a -> b #

foldl :: (b -> a -> b) -> b -> UAddr a -> b #

foldl' :: (b -> a -> b) -> b -> UAddr a -> b #

foldr1 :: (a -> a -> a) -> UAddr a -> a #

foldl1 :: (a -> a -> a) -> UAddr a -> a #

toList :: UAddr a -> [a] #

null :: UAddr a -> Bool #

length :: UAddr a -> Int #

elem :: Eq a => a -> UAddr a -> Bool #

maximum :: Ord a => UAddr a -> a #

minimum :: Ord a => UAddr a -> a #

sum :: Num a => UAddr a -> a #

product :: Num a => UAddr a -> a #

Foldable (UChar :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UChar m -> m #

foldMap :: Monoid m => (a -> m) -> UChar a -> m #

foldMap' :: Monoid m => (a -> m) -> UChar a -> m #

foldr :: (a -> b -> b) -> b -> UChar a -> b #

foldr' :: (a -> b -> b) -> b -> UChar a -> b #

foldl :: (b -> a -> b) -> b -> UChar a -> b #

foldl' :: (b -> a -> b) -> b -> UChar a -> b #

foldr1 :: (a -> a -> a) -> UChar a -> a #

foldl1 :: (a -> a -> a) -> UChar a -> a #

toList :: UChar a -> [a] #

null :: UChar a -> Bool #

length :: UChar a -> Int #

elem :: Eq a => a -> UChar a -> Bool #

maximum :: Ord a => UChar a -> a #

minimum :: Ord a => UChar a -> a #

sum :: Num a => UChar a -> a #

product :: Num a => UChar a -> a #

Foldable (UDouble :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UDouble m -> m #

foldMap :: Monoid m => (a -> m) -> UDouble a -> m #

foldMap' :: Monoid m => (a -> m) -> UDouble a -> m #

foldr :: (a -> b -> b) -> b -> UDouble a -> b #

foldr' :: (a -> b -> b) -> b -> UDouble a -> b #

foldl :: (b -> a -> b) -> b -> UDouble a -> b #

foldl' :: (b -> a -> b) -> b -> UDouble a -> b #

foldr1 :: (a -> a -> a) -> UDouble a -> a #

foldl1 :: (a -> a -> a) -> UDouble a -> a #

toList :: UDouble a -> [a] #

null :: UDouble a -> Bool #

length :: UDouble a -> Int #

elem :: Eq a => a -> UDouble a -> Bool #

maximum :: Ord a => UDouble a -> a #

minimum :: Ord a => UDouble a -> a #

sum :: Num a => UDouble a -> a #

product :: Num a => UDouble a -> a #

Foldable (UFloat :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UFloat m -> m #

foldMap :: Monoid m => (a -> m) -> UFloat a -> m #

foldMap' :: Monoid m => (a -> m) -> UFloat a -> m #

foldr :: (a -> b -> b) -> b -> UFloat a -> b #

foldr' :: (a -> b -> b) -> b -> UFloat a -> b #

foldl :: (b -> a -> b) -> b -> UFloat a -> b #

foldl' :: (b -> a -> b) -> b -> UFloat a -> b #

foldr1 :: (a -> a -> a) -> UFloat a -> a #

foldl1 :: (a -> a -> a) -> UFloat a -> a #

toList :: UFloat a -> [a] #

null :: UFloat a -> Bool #

length :: UFloat a -> Int #

elem :: Eq a => a -> UFloat a -> Bool #

maximum :: Ord a => UFloat a -> a #

minimum :: Ord a => UFloat a -> a #

sum :: Num a => UFloat a -> a #

product :: Num a => UFloat a -> a #

Foldable (UInt :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UInt m -> m #

foldMap :: Monoid m => (a -> m) -> UInt a -> m #

foldMap' :: Monoid m => (a -> m) -> UInt a -> m #

foldr :: (a -> b -> b) -> b -> UInt a -> b #

foldr' :: (a -> b -> b) -> b -> UInt a -> b #

foldl :: (b -> a -> b) -> b -> UInt a -> b #

foldl' :: (b -> a -> b) -> b -> UInt a -> b #

foldr1 :: (a -> a -> a) -> UInt a -> a #

foldl1 :: (a -> a -> a) -> UInt a -> a #

toList :: UInt a -> [a] #

null :: UInt a -> Bool #

length :: UInt a -> Int #

elem :: Eq a => a -> UInt a -> Bool #

maximum :: Ord a => UInt a -> a #

minimum :: Ord a => UInt a -> a #

sum :: Num a => UInt a -> a #

product :: Num a => UInt a -> a #

Foldable (UWord :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => UWord m -> m #

foldMap :: Monoid m => (a -> m) -> UWord a -> m #

foldMap' :: Monoid m => (a -> m) -> UWord a -> m #

foldr :: (a -> b -> b) -> b -> UWord a -> b #

foldr' :: (a -> b -> b) -> b -> UWord a -> b #

foldl :: (b -> a -> b) -> b -> UWord a -> b #

foldl' :: (b -> a -> b) -> b -> UWord a -> b #

foldr1 :: (a -> a -> a) -> UWord a -> a #

foldl1 :: (a -> a -> a) -> UWord a -> a #

toList :: UWord a -> [a] #

null :: UWord a -> Bool #

length :: UWord a -> Int #

elem :: Eq a => a -> UWord a -> Bool #

maximum :: Ord a => UWord a -> a #

minimum :: Ord a => UWord a -> a #

sum :: Num a => UWord a -> a #

product :: Num a => UWord a -> a #

Foldable (V1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => V1 m -> m #

foldMap :: Monoid m => (a -> m) -> V1 a -> m #

foldMap' :: Monoid m => (a -> m) -> V1 a -> m #

foldr :: (a -> b -> b) -> b -> V1 a -> b #

foldr' :: (a -> b -> b) -> b -> V1 a -> b #

foldl :: (b -> a -> b) -> b -> V1 a -> b #

foldl' :: (b -> a -> b) -> b -> V1 a -> b #

foldr1 :: (a -> a -> a) -> V1 a -> a #

foldl1 :: (a -> a -> a) -> V1 a -> a #

toList :: V1 a -> [a] #

null :: V1 a -> Bool #

length :: V1 a -> Int #

elem :: Eq a => a -> V1 a -> Bool #

maximum :: Ord a => V1 a -> a #

minimum :: Ord a => V1 a -> a #

sum :: Num a => V1 a -> a #

product :: Num a => V1 a -> a #

Foldable ((,) a)

Since: base-4.7.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (a, m) -> m #

foldMap :: Monoid m => (a0 -> m) -> (a, a0) -> m #

foldMap' :: Monoid m => (a0 -> m) -> (a, a0) -> m #

foldr :: (a0 -> b -> b) -> b -> (a, a0) -> b #

foldr' :: (a0 -> b -> b) -> b -> (a, a0) -> b #

foldl :: (b -> a0 -> b) -> b -> (a, a0) -> b #

foldl' :: (b -> a0 -> b) -> b -> (a, a0) -> b #

foldr1 :: (a0 -> a0 -> a0) -> (a, a0) -> a0 #

foldl1 :: (a0 -> a0 -> a0) -> (a, a0) -> a0 #

toList :: (a, a0) -> [a0] #

null :: (a, a0) -> Bool #

length :: (a, a0) -> Int #

elem :: Eq a0 => a0 -> (a, a0) -> Bool #

maximum :: Ord a0 => (a, a0) -> a0 #

minimum :: Ord a0 => (a, a0) -> a0 #

sum :: Num a0 => (a, a0) -> a0 #

product :: Num a0 => (a, a0) -> a0 #

Foldable (Const m :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in Data.Functor.Const

Methods

fold :: Monoid m0 => Const m m0 -> m0 #

foldMap :: Monoid m0 => (a -> m0) -> Const m a -> m0 #

foldMap' :: Monoid m0 => (a -> m0) -> Const m a -> m0 #

foldr :: (a -> b -> b) -> b -> Const m a -> b #

foldr' :: (a -> b -> b) -> b -> Const m a -> b #

foldl :: (b -> a -> b) -> b -> Const m a -> b #

foldl' :: (b -> a -> b) -> b -> Const m a -> b #

foldr1 :: (a -> a -> a) -> Const m a -> a #

foldl1 :: (a -> a -> a) -> Const m a -> a #

toList :: Const m a -> [a] #

null :: Const m a -> Bool #

length :: Const m a -> Int #

elem :: Eq a => a -> Const m a -> Bool #

maximum :: Ord a => Const m a -> a #

minimum :: Ord a => Const m a -> a #

sum :: Num a => Const m a -> a #

product :: Num a => Const m a -> a #

Foldable f => Foldable (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Ap f m -> m #

foldMap :: Monoid m => (a -> m) -> Ap f a -> m #

foldMap' :: Monoid m => (a -> m) -> Ap f a -> m #

foldr :: (a -> b -> b) -> b -> Ap f a -> b #

foldr' :: (a -> b -> b) -> b -> Ap f a -> b #

foldl :: (b -> a -> b) -> b -> Ap f a -> b #

foldl' :: (b -> a -> b) -> b -> Ap f a -> b #

foldr1 :: (a -> a -> a) -> Ap f a -> a #

foldl1 :: (a -> a -> a) -> Ap f a -> a #

toList :: Ap f a -> [a] #

null :: Ap f a -> Bool #

length :: Ap f a -> Int #

elem :: Eq a => a -> Ap f a -> Bool #

maximum :: Ord a => Ap f a -> a #

minimum :: Ord a => Ap f a -> a #

sum :: Num a => Ap f a -> a #

product :: Num a => Ap f a -> a #

Foldable f => Foldable (Alt f)

Since: base-4.12.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Alt f m -> m #

foldMap :: Monoid m => (a -> m) -> Alt f a -> m #

foldMap' :: Monoid m => (a -> m) -> Alt f a -> m #

foldr :: (a -> b -> b) -> b -> Alt f a -> b #

foldr' :: (a -> b -> b) -> b -> Alt f a -> b #

foldl :: (b -> a -> b) -> b -> Alt f a -> b #

foldl' :: (b -> a -> b) -> b -> Alt f a -> b #

foldr1 :: (a -> a -> a) -> Alt f a -> a #

foldl1 :: (a -> a -> a) -> Alt f a -> a #

toList :: Alt f a -> [a] #

null :: Alt f a -> Bool #

length :: Alt f a -> Int #

elem :: Eq a => a -> Alt f a -> Bool #

maximum :: Ord a => Alt f a -> a #

minimum :: Ord a => Alt f a -> a #

sum :: Num a => Alt f a -> a #

product :: Num a => Alt f a -> a #

Foldable f => Foldable (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => Rec1 f m -> m #

foldMap :: Monoid m => (a -> m) -> Rec1 f a -> m #

foldMap' :: Monoid m => (a -> m) -> Rec1 f a -> m #

foldr :: (a -> b -> b) -> b -> Rec1 f a -> b #

foldr' :: (a -> b -> b) -> b -> Rec1 f a -> b #

foldl :: (b -> a -> b) -> b -> Rec1 f a -> b #

foldl' :: (b -> a -> b) -> b -> Rec1 f a -> b #

foldr1 :: (a -> a -> a) -> Rec1 f a -> a #

foldl1 :: (a -> a -> a) -> Rec1 f a -> a #

toList :: Rec1 f a -> [a] #

null :: Rec1 f a -> Bool #

length :: Rec1 f a -> Int #

elem :: Eq a => a -> Rec1 f a -> Bool #

maximum :: Ord a => Rec1 f a -> a #

minimum :: Ord a => Rec1 f a -> a #

sum :: Num a => Rec1 f a -> a #

product :: Num a => Rec1 f a -> a #

(Foldable f, Foldable g) => Foldable (f :*: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (f :*: g) m -> m #

foldMap :: Monoid m => (a -> m) -> (f :*: g) a -> m #

foldMap' :: Monoid m => (a -> m) -> (f :*: g) a -> m #

foldr :: (a -> b -> b) -> b -> (f :*: g) a -> b #

foldr' :: (a -> b -> b) -> b -> (f :*: g) a -> b #

foldl :: (b -> a -> b) -> b -> (f :*: g) a -> b #

foldl' :: (b -> a -> b) -> b -> (f :*: g) a -> b #

foldr1 :: (a -> a -> a) -> (f :*: g) a -> a #

foldl1 :: (a -> a -> a) -> (f :*: g) a -> a #

toList :: (f :*: g) a -> [a] #

null :: (f :*: g) a -> Bool #

length :: (f :*: g) a -> Int #

elem :: Eq a => a -> (f :*: g) a -> Bool #

maximum :: Ord a => (f :*: g) a -> a #

minimum :: Ord a => (f :*: g) a -> a #

sum :: Num a => (f :*: g) a -> a #

product :: Num a => (f :*: g) a -> a #

(Foldable f, Foldable g) => Foldable (f :+: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (f :+: g) m -> m #

foldMap :: Monoid m => (a -> m) -> (f :+: g) a -> m #

foldMap' :: Monoid m => (a -> m) -> (f :+: g) a -> m #

foldr :: (a -> b -> b) -> b -> (f :+: g) a -> b #

foldr' :: (a -> b -> b) -> b -> (f :+: g) a -> b #

foldl :: (b -> a -> b) -> b -> (f :+: g) a -> b #

foldl' :: (b -> a -> b) -> b -> (f :+: g) a -> b #

foldr1 :: (a -> a -> a) -> (f :+: g) a -> a #

foldl1 :: (a -> a -> a) -> (f :+: g) a -> a #

toList :: (f :+: g) a -> [a] #

null :: (f :+: g) a -> Bool #

length :: (f :+: g) a -> Int #

elem :: Eq a => a -> (f :+: g) a -> Bool #

maximum :: Ord a => (f :+: g) a -> a #

minimum :: Ord a => (f :+: g) a -> a #

sum :: Num a => (f :+: g) a -> a #

product :: Num a => (f :+: g) a -> a #

Foldable (K1 i c :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => K1 i c m -> m #

foldMap :: Monoid m => (a -> m) -> K1 i c a -> m #

foldMap' :: Monoid m => (a -> m) -> K1 i c a -> m #

foldr :: (a -> b -> b) -> b -> K1 i c a -> b #

foldr' :: (a -> b -> b) -> b -> K1 i c a -> b #

foldl :: (b -> a -> b) -> b -> K1 i c a -> b #

foldl' :: (b -> a -> b) -> b -> K1 i c a -> b #

foldr1 :: (a -> a -> a) -> K1 i c a -> a #

foldl1 :: (a -> a -> a) -> K1 i c a -> a #

toList :: K1 i c a -> [a] #

null :: K1 i c a -> Bool #

length :: K1 i c a -> Int #

elem :: Eq a => a -> K1 i c a -> Bool #

maximum :: Ord a => K1 i c a -> a #

minimum :: Ord a => K1 i c a -> a #

sum :: Num a => K1 i c a -> a #

product :: Num a => K1 i c a -> a #

(Foldable f, Foldable g) => Foldable (f :.: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => (f :.: g) m -> m #

foldMap :: Monoid m => (a -> m) -> (f :.: g) a -> m #

foldMap' :: Monoid m => (a -> m) -> (f :.: g) a -> m #

foldr :: (a -> b -> b) -> b -> (f :.: g) a -> b #

foldr' :: (a -> b -> b) -> b -> (f :.: g) a -> b #

foldl :: (b -> a -> b) -> b -> (f :.: g) a -> b #

foldl' :: (b -> a -> b) -> b -> (f :.: g) a -> b #

foldr1 :: (a -> a -> a) -> (f :.: g) a -> a #

foldl1 :: (a -> a -> a) -> (f :.: g) a -> a #

toList :: (f :.: g) a -> [a] #

null :: (f :.: g) a -> Bool #

length :: (f :.: g) a -> Int #

elem :: Eq a => a -> (f :.: g) a -> Bool #

maximum :: Ord a => (f :.: g) a -> a #

minimum :: Ord a => (f :.: g) a -> a #

sum :: Num a => (f :.: g) a -> a #

product :: Num a => (f :.: g) a -> a #

Foldable f => Foldable (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in Data.Foldable

Methods

fold :: Monoid m => M1 i c f m -> m #

foldMap :: Monoid m => (a -> m) -> M1 i c f a -> m #

foldMap' :: Monoid m => (a -> m) -> M1 i c f a -> m #

foldr :: (a -> b -> b) -> b -> M1 i c f a -> b #

foldr' :: (a -> b -> b) -> b -> M1 i c f a -> b #

foldl :: (b -> a -> b) -> b -> M1 i c f a -> b #

foldl' :: (b -> a -> b) -> b -> M1 i c f a -> b #

foldr1 :: (a -> a -> a) -> M1 i c f a -> a #

foldl1 :: (a -> a -> a) -> M1 i c f a -> a #

toList :: M1 i c f a -> [a] #

null :: M1 i c f a -> Bool #

length :: M1 i c f a -> Int #

elem :: Eq a => a -> M1 i c f a -> Bool #

maximum :: Ord a => M1 i c f a -> a #

minimum :: Ord a => M1 i c f a -> a #

sum :: Num a => M1 i c f a -> a #

product :: Num a => M1 i c f a -> a #

class (Functor t, Foldable t) => Traversable (t :: Type -> Type) where #

Functors representing data structures that can be transformed to structures of the same shape by performing an Applicative (or, therefore, Monad) action on each element from left to right.

A more detailed description of what same shape means, the various methods, how traversals are constructed, and example advanced use-cases can be found in the Overview section of Data.Traversable.

For the class laws see the Laws section of Data.Traversable.

Minimal complete definition

traverse | sequenceA

Methods

traverse :: Applicative f => (a -> f b) -> t a -> f (t b) #

Map each element of a structure to an action, evaluate these actions from left to right, and collect the results. For a version that ignores the results see traverse_.

Examples

Expand

Basic usage:

In the first two examples we show each evaluated action mapping to the output structure.

>>> traverse Just [1,2,3,4]
Just [1,2,3,4]
>>> traverse id [Right 1, Right 2, Right 3, Right 4]
Right [1,2,3,4]

In the next examples, we show that Nothing and Left values short circuit the created structure.

>>> traverse (const Nothing) [1,2,3,4]
Nothing
>>> traverse (\x -> if odd x then Just x else Nothing)  [1,2,3,4]
Nothing
>>> traverse id [Right 1, Right 2, Right 3, Right 4, Left 0]
Left 0

sequenceA :: Applicative f => t (f a) -> f (t a) #

Evaluate each action in the structure from left to right, and collect the results. For a version that ignores the results see sequenceA_.

Examples

Expand

Basic usage:

For the first two examples we show sequenceA fully evaluating a a structure and collecting the results.

>>> sequenceA [Just 1, Just 2, Just 3]
Just [1,2,3]
>>> sequenceA [Right 1, Right 2, Right 3]
Right [1,2,3]

The next two example show Nothing and Just will short circuit the resulting structure if present in the input. For more context, check the Traversable instances for Either and Maybe.

>>> sequenceA [Just 1, Just 2, Just 3, Nothing]
Nothing
>>> sequenceA [Right 1, Right 2, Right 3, Left 4]
Left 4

mapM :: Monad m => (a -> m b) -> t a -> m (t b) #

Map each element of a structure to a monadic action, evaluate these actions from left to right, and collect the results. For a version that ignores the results see mapM_.

Examples

Expand

mapM is literally a traverse with a type signature restricted to Monad. Its implementation may be more efficient due to additional power of Monad.

sequence :: Monad m => t (m a) -> m (t a) #

Evaluate each monadic action in the structure from left to right, and collect the results. For a version that ignores the results see sequence_.

Examples

Expand

Basic usage:

The first two examples are instances where the input and and output of sequence are isomorphic.

>>> sequence $ Right [1,2,3,4]
[Right 1,Right 2,Right 3,Right 4]
>>> sequence $ [Right 1,Right 2,Right 3,Right 4]
Right [1,2,3,4]

The following examples demonstrate short circuit behavior for sequence.

>>> sequence $ Left [1,2,3,4]
Left [1,2,3,4]
>>> sequence $ [Left 0, Right 1,Right 2,Right 3,Right 4]
Left 0

Instances

Instances details
Traversable ZipList

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> ZipList a -> f (ZipList b) #

sequenceA :: Applicative f => ZipList (f a) -> f (ZipList a) #

mapM :: Monad m => (a -> m b) -> ZipList a -> m (ZipList b) #

sequence :: Monad m => ZipList (m a) -> m (ZipList a) #

Traversable Identity

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Identity a -> f (Identity b) #

sequenceA :: Applicative f => Identity (f a) -> f (Identity a) #

mapM :: Monad m => (a -> m b) -> Identity a -> m (Identity b) #

sequence :: Monad m => Identity (m a) -> m (Identity a) #

Traversable First

Since: base-4.8.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> First a -> f (First b) #

sequenceA :: Applicative f => First (f a) -> f (First a) #

mapM :: Monad m => (a -> m b) -> First a -> m (First b) #

sequence :: Monad m => First (m a) -> m (First a) #

Traversable Last

Since: base-4.8.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Last a -> f (Last b) #

sequenceA :: Applicative f => Last (f a) -> f (Last a) #

mapM :: Monad m => (a -> m b) -> Last a -> m (Last b) #

sequence :: Monad m => Last (m a) -> m (Last a) #

Traversable Down

Since: base-4.12.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Down a -> f (Down b) #

sequenceA :: Applicative f => Down (f a) -> f (Down a) #

mapM :: Monad m => (a -> m b) -> Down a -> m (Down b) #

sequence :: Monad m => Down (m a) -> m (Down a) #

Traversable First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a -> f b) -> First a -> f (First b) #

sequenceA :: Applicative f => First (f a) -> f (First a) #

mapM :: Monad m => (a -> m b) -> First a -> m (First b) #

sequence :: Monad m => First (m a) -> m (First a) #

Traversable Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a -> f b) -> Last a -> f (Last b) #

sequenceA :: Applicative f => Last (f a) -> f (Last a) #

mapM :: Monad m => (a -> m b) -> Last a -> m (Last b) #

sequence :: Monad m => Last (m a) -> m (Last a) #

Traversable Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a -> f b) -> Max a -> f (Max b) #

sequenceA :: Applicative f => Max (f a) -> f (Max a) #

mapM :: Monad m => (a -> m b) -> Max a -> m (Max b) #

sequence :: Monad m => Max (m a) -> m (Max a) #

Traversable Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a -> f b) -> Min a -> f (Min b) #

sequenceA :: Applicative f => Min (f a) -> f (Min a) #

mapM :: Monad m => (a -> m b) -> Min a -> m (Min b) #

sequence :: Monad m => Min (m a) -> m (Min a) #

Traversable Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Dual a -> f (Dual b) #

sequenceA :: Applicative f => Dual (f a) -> f (Dual a) #

mapM :: Monad m => (a -> m b) -> Dual a -> m (Dual b) #

sequence :: Monad m => Dual (m a) -> m (Dual a) #

Traversable Product

Since: base-4.8.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Product a -> f (Product b) #

sequenceA :: Applicative f => Product (f a) -> f (Product a) #

mapM :: Monad m => (a -> m b) -> Product a -> m (Product b) #

sequence :: Monad m => Product (m a) -> m (Product a) #

Traversable Sum

Since: base-4.8.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Sum a -> f (Sum b) #

sequenceA :: Applicative f => Sum (f a) -> f (Sum a) #

mapM :: Monad m => (a -> m b) -> Sum a -> m (Sum b) #

sequence :: Monad m => Sum (m a) -> m (Sum a) #

Traversable NonEmpty

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> NonEmpty a -> f (NonEmpty b) #

sequenceA :: Applicative f => NonEmpty (f a) -> f (NonEmpty a) #

mapM :: Monad m => (a -> m b) -> NonEmpty a -> m (NonEmpty b) #

sequence :: Monad m => NonEmpty (m a) -> m (NonEmpty a) #

Traversable Par1

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Par1 a -> f (Par1 b) #

sequenceA :: Applicative f => Par1 (f a) -> f (Par1 a) #

mapM :: Monad m => (a -> m b) -> Par1 a -> m (Par1 b) #

sequence :: Monad m => Par1 (m a) -> m (Par1 a) #

Traversable Maybe

Since: base-2.1

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Maybe a -> f (Maybe b) #

sequenceA :: Applicative f => Maybe (f a) -> f (Maybe a) #

mapM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) #

sequence :: Monad m => Maybe (m a) -> m (Maybe a) #

Traversable Solo

Since: base-4.15

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Solo a -> f (Solo b) #

sequenceA :: Applicative f => Solo (f a) -> f (Solo a) #

mapM :: Monad m => (a -> m b) -> Solo a -> m (Solo b) #

sequence :: Monad m => Solo (m a) -> m (Solo a) #

Traversable List

Since: base-2.1

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> [a] -> f [b] #

sequenceA :: Applicative f => [f a] -> f [a] #

mapM :: Monad m => (a -> m b) -> [a] -> m [b] #

sequence :: Monad m => [m a] -> m [a] #

Traversable (Either a)

Since: base-4.7.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a0 -> f b) -> Either a a0 -> f (Either a b) #

sequenceA :: Applicative f => Either a (f a0) -> f (Either a a0) #

mapM :: Monad m => (a0 -> m b) -> Either a a0 -> m (Either a b) #

sequence :: Monad m => Either a (m a0) -> m (Either a a0) #

Traversable (Proxy :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Proxy a -> f (Proxy b) #

sequenceA :: Applicative f => Proxy (f a) -> f (Proxy a) #

mapM :: Monad m => (a -> m b) -> Proxy a -> m (Proxy b) #

sequence :: Monad m => Proxy (m a) -> m (Proxy a) #

Traversable (Arg a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

traverse :: Applicative f => (a0 -> f b) -> Arg a a0 -> f (Arg a b) #

sequenceA :: Applicative f => Arg a (f a0) -> f (Arg a a0) #

mapM :: Monad m => (a0 -> m b) -> Arg a a0 -> m (Arg a b) #

sequence :: Monad m => Arg a (m a0) -> m (Arg a a0) #

Ix i => Traversable (Array i)

Since: base-2.1

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Array i a -> f (Array i b) #

sequenceA :: Applicative f => Array i (f a) -> f (Array i a) #

mapM :: Monad m => (a -> m b) -> Array i a -> m (Array i b) #

sequence :: Monad m => Array i (m a) -> m (Array i a) #

Traversable (U1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> U1 a -> f (U1 b) #

sequenceA :: Applicative f => U1 (f a) -> f (U1 a) #

mapM :: Monad m => (a -> m b) -> U1 a -> m (U1 b) #

sequence :: Monad m => U1 (m a) -> m (U1 a) #

Traversable (UAddr :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UAddr a -> f (UAddr b) #

sequenceA :: Applicative f => UAddr (f a) -> f (UAddr a) #

mapM :: Monad m => (a -> m b) -> UAddr a -> m (UAddr b) #

sequence :: Monad m => UAddr (m a) -> m (UAddr a) #

Traversable (UChar :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UChar a -> f (UChar b) #

sequenceA :: Applicative f => UChar (f a) -> f (UChar a) #

mapM :: Monad m => (a -> m b) -> UChar a -> m (UChar b) #

sequence :: Monad m => UChar (m a) -> m (UChar a) #

Traversable (UDouble :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UDouble a -> f (UDouble b) #

sequenceA :: Applicative f => UDouble (f a) -> f (UDouble a) #

mapM :: Monad m => (a -> m b) -> UDouble a -> m (UDouble b) #

sequence :: Monad m => UDouble (m a) -> m (UDouble a) #

Traversable (UFloat :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UFloat a -> f (UFloat b) #

sequenceA :: Applicative f => UFloat (f a) -> f (UFloat a) #

mapM :: Monad m => (a -> m b) -> UFloat a -> m (UFloat b) #

sequence :: Monad m => UFloat (m a) -> m (UFloat a) #

Traversable (UInt :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UInt a -> f (UInt b) #

sequenceA :: Applicative f => UInt (f a) -> f (UInt a) #

mapM :: Monad m => (a -> m b) -> UInt a -> m (UInt b) #

sequence :: Monad m => UInt (m a) -> m (UInt a) #

Traversable (UWord :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> UWord a -> f (UWord b) #

sequenceA :: Applicative f => UWord (f a) -> f (UWord a) #

mapM :: Monad m => (a -> m b) -> UWord a -> m (UWord b) #

sequence :: Monad m => UWord (m a) -> m (UWord a) #

Traversable (V1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> V1 a -> f (V1 b) #

sequenceA :: Applicative f => V1 (f a) -> f (V1 a) #

mapM :: Monad m => (a -> m b) -> V1 a -> m (V1 b) #

sequence :: Monad m => V1 (m a) -> m (V1 a) #

Traversable ((,) a)

Since: base-4.7.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a0 -> f b) -> (a, a0) -> f (a, b) #

sequenceA :: Applicative f => (a, f a0) -> f (a, a0) #

mapM :: Monad m => (a0 -> m b) -> (a, a0) -> m (a, b) #

sequence :: Monad m => (a, m a0) -> m (a, a0) #

Traversable (Const m :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Const m a -> f (Const m b) #

sequenceA :: Applicative f => Const m (f a) -> f (Const m a) #

mapM :: Monad m0 => (a -> m0 b) -> Const m a -> m0 (Const m b) #

sequence :: Monad m0 => Const m (m0 a) -> m0 (Const m a) #

Traversable f => Traversable (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f0 => (a -> f0 b) -> Ap f a -> f0 (Ap f b) #

sequenceA :: Applicative f0 => Ap f (f0 a) -> f0 (Ap f a) #

mapM :: Monad m => (a -> m b) -> Ap f a -> m (Ap f b) #

sequence :: Monad m => Ap f (m a) -> m (Ap f a) #

Traversable f => Traversable (Alt f)

Since: base-4.12.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f0 => (a -> f0 b) -> Alt f a -> f0 (Alt f b) #

sequenceA :: Applicative f0 => Alt f (f0 a) -> f0 (Alt f a) #

mapM :: Monad m => (a -> m b) -> Alt f a -> m (Alt f b) #

sequence :: Monad m => Alt f (m a) -> m (Alt f a) #

Traversable f => Traversable (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f0 => (a -> f0 b) -> Rec1 f a -> f0 (Rec1 f b) #

sequenceA :: Applicative f0 => Rec1 f (f0 a) -> f0 (Rec1 f a) #

mapM :: Monad m => (a -> m b) -> Rec1 f a -> m (Rec1 f b) #

sequence :: Monad m => Rec1 f (m a) -> m (Rec1 f a) #

(Traversable f, Traversable g) => Traversable (f :*: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f0 => (a -> f0 b) -> (f :*: g) a -> f0 ((f :*: g) b) #

sequenceA :: Applicative f0 => (f :*: g) (f0 a) -> f0 ((f :*: g) a) #

mapM :: Monad m => (a -> m b) -> (f :*: g) a -> m ((f :*: g) b) #

sequence :: Monad m => (f :*: g) (m a) -> m ((f :*: g) a) #

(Traversable f, Traversable g) => Traversable (f :+: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f0 => (a -> f0 b) -> (f :+: g) a -> f0 ((f :+: g) b) #

sequenceA :: Applicative f0 => (f :+: g) (f0 a) -> f0 ((f :+: g) a) #

mapM :: Monad m => (a -> m b) -> (f :+: g) a -> m ((f :+: g) b) #

sequence :: Monad m => (f :+: g) (m a) -> m ((f :+: g) a) #

Traversable (K1 i c :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> K1 i c a -> f (K1 i c b) #

sequenceA :: Applicative f => K1 i c (f a) -> f (K1 i c a) #

mapM :: Monad m => (a -> m b) -> K1 i c a -> m (K1 i c b) #

sequence :: Monad m => K1 i c (m a) -> m (K1 i c a) #

(Traversable f, Traversable g) => Traversable (f :.: g)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f0 => (a -> f0 b) -> (f :.: g) a -> f0 ((f :.: g) b) #

sequenceA :: Applicative f0 => (f :.: g) (f0 a) -> f0 ((f :.: g) a) #

mapM :: Monad m => (a -> m b) -> (f :.: g) a -> m ((f :.: g) b) #

sequence :: Monad m => (f :.: g) (m a) -> m ((f :.: g) a) #

Traversable f => Traversable (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Methods

traverse :: Applicative f0 => (a -> f0 b) -> M1 i c f a -> f0 (M1 i c f b) #

sequenceA :: Applicative f0 => M1 i c f (f0 a) -> f0 (M1 i c f a) #

mapM :: Monad m => (a -> m b) -> M1 i c f a -> m (M1 i c f b) #

sequence :: Monad m => M1 i c f (m a) -> m (M1 i c f a) #

type ShowS = String -> String #

The shows functions return a function that prepends the output String to an existing String. This allows constant-time concatenation of results using function composition.

type ReadS a = String -> [(a, String)] #

A parser for a type a, represented as a function that takes a String and returns a list of possible parses as (a,String) pairs.

Note that this kind of backtracking parser is very inefficient; reading a large structure may be quite slow (cf ReadP).

type FilePath = String #

File and directory names are values of type String, whose precise meaning is operating system dependent. Files can be opened, yielding a handle which can then be used to operate on the contents of that file.

realToFrac :: (Real a, Fractional b) => a -> b #

General coercion to Fractional types.

WARNING: This function goes through the Rational type, which does not have values for NaN for example. This means it does not round-trip.

For Double it also behaves differently with or without -O0:

Prelude> realToFrac nan -- With -O0
-Infinity
Prelude> realToFrac nan
NaN

($) :: forall (r :: RuntimeRep) a (b :: TYPE r). (a -> b) -> a -> b infixr 0 #

Application operator. This operator is redundant, since ordinary application (f x) means the same as (f $ x). However, $ has low, right-associative binding precedence, so it sometimes allows parentheses to be omitted; for example:

f $ g $ h x  =  f (g (h x))

It is also useful in higher-order situations, such as map ($ 0) xs, or zipWith ($) fs xs.

Note that ($) is representation-polymorphic in its result type, so that foo $ True where foo :: Bool -> Int# is well-typed.

otherwise :: Bool #

otherwise is defined as the value True. It helps to make guards more readable. eg.

 f x | x < 0     = ...
     | otherwise = ...

(++) :: [a] -> [a] -> [a] infixr 5 #

Append two lists, i.e.,

[x1, ..., xm] ++ [y1, ..., yn] == [x1, ..., xm, y1, ..., yn]
[x1, ..., xm] ++ [y1, ...] == [x1, ..., xm, y1, ...]

If the first list is not finite, the result is the first list.

WARNING: This function takes linear time in the number of elements of the first list.

map :: (a -> b) -> [a] -> [b] #

\(\mathcal{O}(n)\). map f xs is the list obtained by applying f to each element of xs, i.e.,

map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
map f [x1, x2, ...] == [f x1, f x2, ...]
>>> map (+1) [1, 2, 3]
[2,3,4]

error :: forall (r :: RuntimeRep) (a :: TYPE r). HasCallStack => [Char] -> a #

error stops execution and displays an error message.

zipWith :: (a -> b -> c) -> [a] -> [b] -> [c] #

\(\mathcal{O}(\min(m,n))\). zipWith generalises zip by zipping with the function given as the first argument, instead of a tupling function.

zipWith (,) xs ys == zip xs ys
zipWith f [x1,x2,x3..] [y1,y2,y3..] == [f x1 y1, f x2 y2, f x3 y3..]

For example, zipWith (+) is applied to two lists to produce the list of corresponding sums:

>>> zipWith (+) [1, 2, 3] [4, 5, 6]
[5,7,9]

zipWith is right-lazy:

>>> let f = undefined
>>> zipWith f [] undefined
[]

zipWith is capable of list fusion, but it is restricted to its first list argument and its resulting list.

(<$>) :: Functor f => (a -> b) -> f a -> f b infixl 4 #

An infix synonym for fmap.

The name of this operator is an allusion to $. Note the similarities between their types:

 ($)  ::              (a -> b) ->   a ->   b
(<$>) :: Functor f => (a -> b) -> f a -> f b

Whereas $ is function application, <$> is function application lifted over a Functor.

Examples

Expand

Convert from a Maybe Int to a Maybe String using show:

>>> show <$> Nothing
Nothing
>>> show <$> Just 3
Just "3"

Convert from an Either Int Int to an Either Int String using show:

>>> show <$> Left 17
Left 17
>>> show <$> Right 17
Right "17"

Double each element of a list:

>>> (*2) <$> [1,2,3]
[2,4,6]

Apply even to the second element of a pair:

>>> even <$> (2,2)
(2,True)

fst :: (a, b) -> a #

Extract the first component of a pair.

uncurry :: (a -> b -> c) -> (a, b) -> c #

uncurry converts a curried function to a function on pairs.

Examples

Expand
>>> uncurry (+) (1,2)
3
>>> uncurry ($) (show, 1)
"1"
>>> map (uncurry max) [(1,2), (3,4), (6,8)]
[2,4,8]

head :: HasCallStack => [a] -> a #

\(\mathcal{O}(1)\). Extract the first element of a list, which must be non-empty.

>>> head [1, 2, 3]
1
>>> head [1..]
1
>>> head []
*** Exception: Prelude.head: empty list

WARNING: This function is partial. You can use case-matching, uncons or listToMaybe instead.

writeFile :: FilePath -> String -> IO () #

The computation writeFile file str function writes the string str, to the file file.

getLine :: IO String #

Read a line from the standard input device (same as hGetLine stdin).

putStrLn :: String -> IO () #

The same as putStr, but adds a newline character.

filter :: (a -> Bool) -> [a] -> [a] #

\(\mathcal{O}(n)\). filter, applied to a predicate and a list, returns the list of those elements that satisfy the predicate; i.e.,

filter p xs = [ x | x <- xs, p x]
>>> filter odd [1, 2, 3]
[1,3]

cycle :: HasCallStack => [a] -> [a] #

cycle ties a finite list into a circular one, or equivalently, the infinite repetition of the original list. It is the identity on infinite lists.

>>> cycle []
*** Exception: Prelude.cycle: empty list
>>> cycle [42]
[42,42,42,42,42,42,42,42,42,42...
>>> cycle [2, 5, 7]
[2,5,7,2,5,7,2,5,7,2,5,7...

seq :: forall {r :: RuntimeRep} a (b :: TYPE r). a -> b -> b infixr 0 #

The value of seq a b is bottom if a is bottom, and otherwise equal to b. In other words, it evaluates the first argument a to weak head normal form (WHNF). seq is usually introduced to improve performance by avoiding unneeded laziness.

A note on evaluation order: the expression seq a b does not guarantee that a will be evaluated before b. The only guarantee given by seq is that the both a and b will be evaluated before seq returns a value. In particular, this means that b may be evaluated before a. If you need to guarantee a specific order of evaluation, you must use the function pseq from the "parallel" package.

concat :: Foldable t => t [a] -> [a] #

The concatenation of all the elements of a container of lists.

Examples

Expand

Basic usage:

>>> concat (Just [1, 2, 3])
[1,2,3]
>>> concat (Left 42)
[]
>>> concat [[1, 2, 3], [4, 5], [6], []]
[1,2,3,4,5,6]

zip :: [a] -> [b] -> [(a, b)] #

\(\mathcal{O}(\min(m,n))\). zip takes two lists and returns a list of corresponding pairs.

>>> zip [1, 2] ['a', 'b']
[(1,'a'),(2,'b')]

If one input list is shorter than the other, excess elements of the longer list are discarded, even if one of the lists is infinite:

>>> zip [1] ['a', 'b']
[(1,'a')]
>>> zip [1, 2] ['a']
[(1,'a')]
>>> zip [] [1..]
[]
>>> zip [1..] []
[]

zip is right-lazy:

>>> zip [] undefined
[]
>>> zip undefined []
*** Exception: Prelude.undefined
...

zip is capable of list fusion, but it is restricted to its first list argument and its resulting list.

print :: Show a => a -> IO () #

The print function outputs a value of any printable type to the standard output device. Printable types are those that are instances of class Show; print converts values to strings for output using the show operation and adds a newline.

For example, a program to print the first 20 integers and their powers of 2 could be written as:

main = print ([(n, 2^n) | n <- [0..19]])

(&&) :: Bool -> Bool -> Bool infixr 3 #

Boolean "and", lazy in the second argument

(||) :: Bool -> Bool -> Bool infixr 2 #

Boolean "or", lazy in the second argument

not :: Bool -> Bool #

Boolean "not"

errorWithoutStackTrace :: forall (r :: RuntimeRep) (a :: TYPE r). [Char] -> a #

A variant of error that does not produce a stack trace.

Since: base-4.9.0.0

undefined :: forall (r :: RuntimeRep) (a :: TYPE r). HasCallStack => a #

A special case of error. It is expected that compilers will recognize this and insert error messages which are more appropriate to the context in which undefined appears.

(=<<) :: Monad m => (a -> m b) -> m a -> m b infixr 1 #

Same as >>=, but with the arguments interchanged.

const :: a -> b -> a #

const x y always evaluates to x, ignoring its second argument.

>>> const 42 "hello"
42
>>> map (const 42) [0..3]
[42,42,42,42]

flip :: (a -> b -> c) -> b -> a -> c #

flip f takes its (first) two arguments in the reverse order of f.

>>> flip (++) "hello" "world"
"worldhello"

($!) :: forall (r :: RuntimeRep) a (b :: TYPE r). (a -> b) -> a -> b infixr 0 #

Strict (call-by-value) application operator. It takes a function and an argument, evaluates the argument to weak head normal form (WHNF), then calls the function with that value.

until :: (a -> Bool) -> (a -> a) -> a -> a #

until p f yields the result of applying f until p holds.

asTypeOf :: a -> a -> a #

asTypeOf is a type-restricted version of const. It is usually used as an infix operator, and its typing forces its first argument (which is usually overloaded) to have the same type as the second.

maybe :: b -> (a -> b) -> Maybe a -> b #

The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

Examples

Expand

Basic usage:

>>> maybe False odd (Just 3)
True
>>> maybe False odd Nothing
False

Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

>>> import Text.Read ( readMaybe )
>>> maybe 0 (*2) (readMaybe "5")
10
>>> maybe 0 (*2) (readMaybe "")
0

Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

>>> maybe "" show (Just 5)
"5"
>>> maybe "" show Nothing
""

tail :: HasCallStack => [a] -> [a] #

\(\mathcal{O}(1)\). Extract the elements after the head of a list, which must be non-empty.

>>> tail [1, 2, 3]
[2,3]
>>> tail [1]
[]
>>> tail []
*** Exception: Prelude.tail: empty list

WARNING: This function is partial. You can use case-matching or uncons instead.

last :: HasCallStack => [a] -> a #

\(\mathcal{O}(n)\). Extract the last element of a list, which must be finite and non-empty.

>>> last [1, 2, 3]
3
>>> last [1..]
* Hangs forever *
>>> last []
*** Exception: Prelude.last: empty list

WARNING: This function is partial. You can use reverse with case-matching, uncons or listToMaybe instead.

init :: HasCallStack => [a] -> [a] #

\(\mathcal{O}(n)\). Return all the elements of a list except the last one. The list must be non-empty.

>>> init [1, 2, 3]
[1,2]
>>> init [1]
[]
>>> init []
*** Exception: Prelude.init: empty list

WARNING: This function is partial. You can use reverse with case-matching or uncons instead.

scanl :: (b -> a -> b) -> b -> [a] -> [b] #

\(\mathcal{O}(n)\). scanl is similar to foldl, but returns a list of successive reduced values from the left:

scanl f z [x1, x2, ...] == [z, z `f` x1, (z `f` x1) `f` x2, ...]

Note that

last (scanl f z xs) == foldl f z xs
>>> scanl (+) 0 [1..4]
[0,1,3,6,10]
>>> scanl (+) 42 []
[42]
>>> scanl (-) 100 [1..4]
[100,99,97,94,90]
>>> scanl (\reversedString nextChar -> nextChar : reversedString) "foo" ['a', 'b', 'c', 'd']
["foo","afoo","bafoo","cbafoo","dcbafoo"]
>>> scanl (+) 0 [1..]
* Hangs forever *

scanl1 :: (a -> a -> a) -> [a] -> [a] #

\(\mathcal{O}(n)\). scanl1 is a variant of scanl that has no starting value argument:

scanl1 f [x1, x2, ...] == [x1, x1 `f` x2, ...]
>>> scanl1 (+) [1..4]
[1,3,6,10]
>>> scanl1 (+) []
[]
>>> scanl1 (-) [1..4]
[1,-1,-4,-8]
>>> scanl1 (&&) [True, False, True, True]
[True,False,False,False]
>>> scanl1 (||) [False, False, True, True]
[False,False,True,True]
>>> scanl1 (+) [1..]
* Hangs forever *

scanr :: (a -> b -> b) -> b -> [a] -> [b] #

\(\mathcal{O}(n)\). scanr is the right-to-left dual of scanl. Note that the order of parameters on the accumulating function are reversed compared to scanl. Also note that

head (scanr f z xs) == foldr f z xs.
>>> scanr (+) 0 [1..4]
[10,9,7,4,0]
>>> scanr (+) 42 []
[42]
>>> scanr (-) 100 [1..4]
[98,-97,99,-96,100]
>>> scanr (\nextChar reversedString -> nextChar : reversedString) "foo" ['a', 'b', 'c', 'd']
["abcdfoo","bcdfoo","cdfoo","dfoo","foo"]
>>> force $ scanr (+) 0 [1..]
*** Exception: stack overflow

scanr1 :: (a -> a -> a) -> [a] -> [a] #

\(\mathcal{O}(n)\). scanr1 is a variant of scanr that has no starting value argument.

>>> scanr1 (+) [1..4]
[10,9,7,4]
>>> scanr1 (+) []
[]
>>> scanr1 (-) [1..4]
[-2,3,-1,4]
>>> scanr1 (&&) [True, False, True, True]
[False,False,True,True]
>>> scanr1 (||) [True, True, False, False]
[True,True,False,False]
>>> force $ scanr1 (+) [1..]
*** Exception: stack overflow

iterate :: (a -> a) -> a -> [a] #

iterate f x returns an infinite list of repeated applications of f to x:

iterate f x == [x, f x, f (f x), ...]

Note that iterate is lazy, potentially leading to thunk build-up if the consumer doesn't force each iterate. See iterate' for a strict variant of this function.

>>> take 10 $ iterate not True
[True,False,True,False...
>>> take 10 $ iterate (+3) 42
[42,45,48,51,54,57,60,63...

repeat :: a -> [a] #

repeat x is an infinite list, with x the value of every element.

>>> repeat 17
[17,17,17,17,17,17,17,17,17...

replicate :: Int -> a -> [a] #

replicate n x is a list of length n with x the value of every element. It is an instance of the more general genericReplicate, in which n may be of any integral type.

>>> replicate 0 True
[]
>>> replicate (-1) True
[]
>>> replicate 4 True
[True,True,True,True]

takeWhile :: (a -> Bool) -> [a] -> [a] #

takeWhile, applied to a predicate p and a list xs, returns the longest prefix (possibly empty) of xs of elements that satisfy p.

>>> takeWhile (< 3) [1,2,3,4,1,2,3,4]
[1,2]
>>> takeWhile (< 9) [1,2,3]
[1,2,3]
>>> takeWhile (< 0) [1,2,3]
[]

dropWhile :: (a -> Bool) -> [a] -> [a] #

dropWhile p xs returns the suffix remaining after takeWhile p xs.

>>> dropWhile (< 3) [1,2,3,4,5,1,2,3]
[3,4,5,1,2,3]
>>> dropWhile (< 9) [1,2,3]
[]
>>> dropWhile (< 0) [1,2,3]
[1,2,3]

take :: Int -> [a] -> [a] #

take n, applied to a list xs, returns the prefix of xs of length n, or xs itself if n >= length xs.

>>> take 5 "Hello World!"
"Hello"
>>> take 3 [1,2,3,4,5]
[1,2,3]
>>> take 3 [1,2]
[1,2]
>>> take 3 []
[]
>>> take (-1) [1,2]
[]
>>> take 0 [1,2]
[]

It is an instance of the more general genericTake, in which n may be of any integral type.

drop :: Int -> [a] -> [a] #

drop n xs returns the suffix of xs after the first n elements, or [] if n >= length xs.

>>> drop 6 "Hello World!"
"World!"
>>> drop 3 [1,2,3,4,5]
[4,5]
>>> drop 3 [1,2]
[]
>>> drop 3 []
[]
>>> drop (-1) [1,2]
[1,2]
>>> drop 0 [1,2]
[1,2]

It is an instance of the more general genericDrop, in which n may be of any integral type.

splitAt :: Int -> [a] -> ([a], [a]) #

splitAt n xs returns a tuple where first element is xs prefix of length n and second element is the remainder of the list:

>>> splitAt 6 "Hello World!"
("Hello ","World!")
>>> splitAt 3 [1,2,3,4,5]
([1,2,3],[4,5])
>>> splitAt 1 [1,2,3]
([1],[2,3])
>>> splitAt 3 [1,2,3]
([1,2,3],[])
>>> splitAt 4 [1,2,3]
([1,2,3],[])
>>> splitAt 0 [1,2,3]
([],[1,2,3])
>>> splitAt (-1) [1,2,3]
([],[1,2,3])

It is equivalent to (take n xs, drop n xs) when n is not _|_ (splitAt _|_ xs = _|_). splitAt is an instance of the more general genericSplitAt, in which n may be of any integral type.

span :: (a -> Bool) -> [a] -> ([a], [a]) #

span, applied to a predicate p and a list xs, returns a tuple where first element is longest prefix (possibly empty) of xs of elements that satisfy p and second element is the remainder of the list:

>>> span (< 3) [1,2,3,4,1,2,3,4]
([1,2],[3,4,1,2,3,4])
>>> span (< 9) [1,2,3]
([1,2,3],[])
>>> span (< 0) [1,2,3]
([],[1,2,3])

span p xs is equivalent to (takeWhile p xs, dropWhile p xs)

break :: (a -> Bool) -> [a] -> ([a], [a]) #

break, applied to a predicate p and a list xs, returns a tuple where first element is longest prefix (possibly empty) of xs of elements that do not satisfy p and second element is the remainder of the list:

>>> break (> 3) [1,2,3,4,1,2,3,4]
([1,2,3],[4,1,2,3,4])
>>> break (< 9) [1,2,3]
([],[1,2,3])
>>> break (> 9) [1,2,3]
([1,2,3],[])

break p is equivalent to span (not . p).

reverse :: [a] -> [a] #

reverse xs returns the elements of xs in reverse order. xs must be finite.

>>> reverse []
[]
>>> reverse [42]
[42]
>>> reverse [2,5,7]
[7,5,2]
>>> reverse [1..]
* Hangs forever *

and :: Foldable t => t Bool -> Bool #

and returns the conjunction of a container of Bools. For the result to be True, the container must be finite; False, however, results from a False value finitely far from the left end.

Examples

Expand

Basic usage:

>>> and []
True
>>> and [True]
True
>>> and [False]
False
>>> and [True, True, False]
False
>>> and (False : repeat True) -- Infinite list [False,True,True,True,...
False
>>> and (repeat True)
* Hangs forever *

or :: Foldable t => t Bool -> Bool #

or returns the disjunction of a container of Bools. For the result to be False, the container must be finite; True, however, results from a True value finitely far from the left end.

Examples

Expand

Basic usage:

>>> or []
False
>>> or [True]
True
>>> or [False]
False
>>> or [True, True, False]
True
>>> or (True : repeat False) -- Infinite list [True,False,False,False,...
True
>>> or (repeat False)
* Hangs forever *

any :: Foldable t => (a -> Bool) -> t a -> Bool #

Determines whether any element of the structure satisfies the predicate.

Examples

Expand

Basic usage:

>>> any (> 3) []
False
>>> any (> 3) [1,2]
False
>>> any (> 3) [1,2,3,4,5]
True
>>> any (> 3) [1..]
True
>>> any (> 3) [0, -1..]
* Hangs forever *

all :: Foldable t => (a -> Bool) -> t a -> Bool #

Determines whether all elements of the structure satisfy the predicate.

Examples

Expand

Basic usage:

>>> all (> 3) []
True
>>> all (> 3) [1,2]
False
>>> all (> 3) [1,2,3,4,5]
False
>>> all (> 3) [1..]
False
>>> all (> 3) [4..]
* Hangs forever *

notElem :: (Foldable t, Eq a) => a -> t a -> Bool infix 4 #

notElem is the negation of elem.

Examples

Expand

Basic usage:

>>> 3 `notElem` []
True
>>> 3 `notElem` [1,2]
True
>>> 3 `notElem` [1,2,3,4,5]
False

For infinite structures, notElem terminates if the value exists at a finite distance from the left side of the structure:

>>> 3 `notElem` [1..]
False
>>> 3 `notElem` ([4..] ++ [3])
* Hangs forever *

lookup :: Eq a => a -> [(a, b)] -> Maybe b #

\(\mathcal{O}(n)\). lookup key assocs looks up a key in an association list. For the result to be Nothing, the list must be finite.

>>> lookup 2 []
Nothing
>>> lookup 2 [(1, "first")]
Nothing
>>> lookup 2 [(1, "first"), (2, "second"), (3, "third")]
Just "second"

concatMap :: Foldable t => (a -> [b]) -> t a -> [b] #

Map a function over all the elements of a container and concatenate the resulting lists.

Examples

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Basic usage:

>>> concatMap (take 3) [[1..], [10..], [100..], [1000..]]
[1,2,3,10,11,12,100,101,102,1000,1001,1002]
>>> concatMap (take 3) (Just [1..])
[1,2,3]

(!!) :: HasCallStack => [a] -> Int -> a infixl 9 #

List index (subscript) operator, starting from 0. It is an instance of the more general genericIndex, which takes an index of any integral type.

>>> ['a', 'b', 'c'] !! 0
'a'
>>> ['a', 'b', 'c'] !! 2
'c'
>>> ['a', 'b', 'c'] !! 3
*** Exception: Prelude.!!: index too large
>>> ['a', 'b', 'c'] !! (-1)
*** Exception: Prelude.!!: negative index

WARNING: This function is partial. You can use atMay instead.

zip3 :: [a] -> [b] -> [c] -> [(a, b, c)] #

zip3 takes three lists and returns a list of triples, analogous to zip. It is capable of list fusion, but it is restricted to its first list argument and its resulting list.

zipWith3 :: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d] #

The zipWith3 function takes a function which combines three elements, as well as three lists and returns a list of the function applied to corresponding elements, analogous to zipWith. It is capable of list fusion, but it is restricted to its first list argument and its resulting list.

zipWith3 (,,) xs ys zs == zip3 xs ys zs
zipWith3 f [x1,x2,x3..] [y1,y2,y3..] [z1,z2,z3..] == [f x1 y1 z1, f x2 y2 z2, f x3 y3 z3..]

unzip :: [(a, b)] -> ([a], [b]) #

unzip transforms a list of pairs into a list of first components and a list of second components.

>>> unzip []
([],[])
>>> unzip [(1, 'a'), (2, 'b')]
([1,2],"ab")

unzip3 :: [(a, b, c)] -> ([a], [b], [c]) #

The unzip3 function takes a list of triples and returns three lists, analogous to unzip.

>>> unzip3 []
([],[],[])
>>> unzip3 [(1, 'a', True), (2, 'b', False)]
([1,2],"ab",[True,False])

shows :: Show a => a -> ShowS #

equivalent to showsPrec with a precedence of 0.

showChar :: Char -> ShowS #

utility function converting a Char to a show function that simply prepends the character unchanged.

showString :: String -> ShowS #

utility function converting a String to a show function that simply prepends the string unchanged.

showParen :: Bool -> ShowS -> ShowS #

utility function that surrounds the inner show function with parentheses when the Bool parameter is True.

lcm :: Integral a => a -> a -> a #

lcm x y is the smallest positive integer that both x and y divide.

snd :: (a, b) -> b #

Extract the second component of a pair.

curry :: ((a, b) -> c) -> a -> b -> c #

curry converts an uncurried function to a curried function.

Examples

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>>> curry fst 1 2
1

lex :: ReadS String #

The lex function reads a single lexeme from the input, discarding initial white space, and returning the characters that constitute the lexeme. If the input string contains only white space, lex returns a single successful `lexeme' consisting of the empty string. (Thus lex "" = [("","")].) If there is no legal lexeme at the beginning of the input string, lex fails (i.e. returns []).

This lexer is not completely faithful to the Haskell lexical syntax in the following respects:

  • Qualified names are not handled properly
  • Octal and hexadecimal numerics are not recognized as a single token
  • Comments are not treated properly

readParen :: Bool -> ReadS a -> ReadS a #

readParen True p parses what p parses, but surrounded with parentheses.

readParen False p parses what p parses, but optionally surrounded with parentheses.

either :: (a -> c) -> (b -> c) -> Either a b -> c #

Case analysis for the Either type. If the value is Left a, apply the first function to a; if it is Right b, apply the second function to b.

Examples

Expand

We create two values of type Either String Int, one using the Left constructor and another using the Right constructor. Then we apply "either" the length function (if we have a String) or the "times-two" function (if we have an Int):

>>> let s = Left "foo" :: Either String Int
>>> let n = Right 3 :: Either String Int
>>> either length (*2) s
3
>>> either length (*2) n
6

reads :: Read a => ReadS a #

equivalent to readsPrec with a precedence of 0.

read :: Read a => String -> a #

The read function reads input from a string, which must be completely consumed by the input process. read fails with an error if the parse is unsuccessful, and it is therefore discouraged from being used in real applications. Use readMaybe or readEither for safe alternatives.

>>> read "123" :: Int
123
>>> read "hello" :: Int
*** Exception: Prelude.read: no parse

mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m () #

Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM.

mapM_ is just like traverse_, but specialised to monadic actions.

sequence_ :: (Foldable t, Monad m) => t (m a) -> m () #

Evaluate each monadic action in the structure from left to right, and ignore the results. For a version that doesn't ignore the results see sequence.

sequence_ is just like sequenceA_, but specialised to monadic actions.

lines :: String -> [String] #

Splits the argument into a list of lines stripped of their terminating \n characters. The \n terminator is optional in a final non-empty line of the argument string.

For example:

>>> lines ""           -- empty input contains no lines
[]
>>> lines "\n"         -- single empty line
[""]
>>> lines "one"        -- single unterminated line
["one"]
>>> lines "one\n"      -- single non-empty line
["one"]
>>> lines "one\n\n"    -- second line is empty
["one",""]
>>> lines "one\ntwo"   -- second line is unterminated
["one","two"]
>>> lines "one\ntwo\n" -- two non-empty lines
["one","two"]

When the argument string is empty, or ends in a \n character, it can be recovered by passing the result of lines to the unlines function. Otherwise, unlines appends the missing terminating \n. This makes unlines . lines idempotent:

(unlines . lines) . (unlines . lines) = (unlines . lines)

unlines :: [String] -> String #

Appends a \n character to each input string, then concatenates the results. Equivalent to foldMap (s -> s ++ "\n").

>>> unlines ["Hello", "World", "!"]
"Hello\nWorld\n!\n"

Note that unlines . lines /= id when the input is not \n-terminated:

>>> unlines . lines $ "foo\nbar"
"foo\nbar\n"

words :: String -> [String] #

words breaks a string up into a list of words, which were delimited by white space (as defined by isSpace). This function trims any white spaces at the beginning and at the end.

>>> words "Lorem ipsum\ndolor"
["Lorem","ipsum","dolor"]
>>> words " foo bar "
["foo","bar"]

unwords :: [String] -> String #

unwords joins words with separating spaces (U+0020 SPACE).

>>> unwords ["Lorem", "ipsum", "dolor"]
"Lorem ipsum dolor"

unwords is neither left nor right inverse of words:

>>> words (unwords [" "])
[]
>>> unwords (words "foo\nbar")
"foo bar"

userError :: String -> IOError #

Construct an IOException value with a string describing the error. The fail method of the IO instance of the Monad class raises a userError, thus:

instance Monad IO where
  ...
  fail s = ioError (userError s)

ioError :: IOError -> IO a #

Raise an IOException in the IO monad.

putChar :: Char -> IO () #

Write a character to the standard output device (same as hPutChar stdout).

putStr :: String -> IO () #

Write a string to the standard output device (same as hPutStr stdout).

getChar :: IO Char #

Read a character from the standard input device (same as hGetChar stdin).

getContents :: IO String #

The getContents operation returns all user input as a single string, which is read lazily as it is needed (same as hGetContents stdin).

interact :: (String -> String) -> IO () #

The interact function takes a function of type String->String as its argument. The entire input from the standard input device is passed to this function as its argument, and the resulting string is output on the standard output device.

readFile :: FilePath -> IO String #

The readFile function reads a file and returns the contents of the file as a string. The file is read lazily, on demand, as with getContents.

appendFile :: FilePath -> String -> IO () #

The computation appendFile file str function appends the string str, to the file file.

Note that writeFile and appendFile write a literal string to a file. To write a value of any printable type, as with print, use the show function to convert the value to a string first.

main = appendFile "squares" (show [(x,x*x) | x <- [0,0.1..2]])

readLn :: Read a => IO a #

The readLn function combines getLine and readIO.

readIO :: Read a => String -> IO a #

The readIO function is similar to read except that it signals parse failure to the IO monad instead of terminating the program.