Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Mostly for compatibility across different base Prelude changes.
Synopsis
- class Semigroup a where
- class Monad m => MonadFail (m :: Type -> Type)
- data Int
- type String = [Char]
- data Bool
- data Char
- data Double
- data Float
- data Word
- data Ordering
- data Maybe a
- class a ~# b => (a :: k) ~ (b :: k)
- data Integer
- data IO a
- class Semigroup a => Monoid a where
- class Semigroup a where
- (<>) :: a -> a -> a
- class Functor f => Applicative (f :: Type -> Type) where
- class Functor (f :: Type -> Type) where
- class Applicative m => Monad (m :: Type -> Type) where
- class (Functor t, Foldable t) => Traversable (t :: Type -> Type) where
- traverse :: Applicative f => (a -> f b) -> t a -> f (t b)
- sequenceA :: Applicative f => t (f a) -> f (t a)
- mapM :: Monad m => (a -> m b) -> t a -> m (t b)
- sequence :: Monad m => t (m a) -> m (t a)
- class Foldable (t :: Type -> Type) where
- foldMap :: Monoid m => (a -> m) -> t a -> m
- foldr :: (a -> b -> b) -> b -> t a -> b
- foldl :: (b -> a -> b) -> b -> t a -> b
- foldr1 :: (a -> a -> a) -> t a -> a
- foldl1 :: (a -> a -> a) -> t a -> a
- null :: t a -> Bool
- length :: t a -> Int
- elem :: Eq a => a -> t a -> Bool
- maximum :: Ord a => t a -> a
- minimum :: Ord a => t a -> a
- sum :: Num a => t a -> a
- product :: Num a => t a -> a
- class Show a where
- data Either a b
- class (Real a, Enum a) => Integral a where
- type Rational = Ratio Integer
- class Read a where
- type IOError = IOException
- class Bounded a where
- class Enum a where
- 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]
- class Eq a where
- class Fractional a => Floating a where
- class Num a => Fractional a where
- (/) :: a -> a -> a
- recip :: a -> a
- fromRational :: Rational -> a
- class Num a where
- class Eq a => Ord a where
- class (Num a, Ord a) => Real a where
- toRational :: a -> Rational
- class (RealFrac a, Floating a) => RealFloat a where
- floatRadix :: a -> Integer
- floatDigits :: a -> Int
- floatRange :: a -> (Int, Int)
- decodeFloat :: a -> (Integer, Int)
- encodeFloat :: Integer -> Int -> a
- exponent :: a -> Int
- significand :: a -> a
- scaleFloat :: Int -> a -> a
- isNaN :: a -> Bool
- isInfinite :: a -> Bool
- isDenormalized :: a -> Bool
- isNegativeZero :: a -> Bool
- isIEEE :: a -> Bool
- atan2 :: a -> a -> a
- class (Real a, Fractional a) => RealFrac a where
- class Monad m => MonadFail (m :: Type -> Type) where
- type ShowS = String -> String
- type ReadS a = String -> [(a, String)]
- type FilePath = String
- ($) :: forall (r :: RuntimeRep) a (b :: TYPE r). (a -> b) -> a -> b
- otherwise :: Bool
- (++) :: [a] -> [a] -> [a]
- mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()
- (=<<) :: Monad m => (a -> m b) -> m a -> m b
- zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]
- zipWith3 :: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
- id :: a -> a
- unzip :: [(a, b)] -> ([a], [b])
- zip :: [a] -> [b] -> [(a, b)]
- concat :: Foldable t => t [a] -> [a]
- error :: forall (r :: RuntimeRep) (a :: TYPE r). HasCallStack => [Char] -> a
- even :: Integral a => a -> Bool
- (<$>) :: Functor f => (a -> b) -> f a -> f b
- fst :: (a, b) -> a
- uncurry :: (a -> b -> c) -> (a, b) -> c
- head :: HasCallStack => [a] -> a
- writeFile :: FilePath -> String -> IO ()
- getLine :: IO String
- putStrLn :: String -> IO ()
- cycle :: HasCallStack => [a] -> [a]
- seq :: forall {r :: RuntimeRep} a (b :: TYPE r). a -> b -> b
- fromIntegral :: (Integral a, Num b) => a -> b
- realToFrac :: (Real a, Fractional b) => a -> b
- (^) :: (Num a, Integral b) => a -> b -> a
- (&&) :: Bool -> Bool -> Bool
- (||) :: Bool -> Bool -> Bool
- not :: Bool -> Bool
- errorWithoutStackTrace :: forall (r :: RuntimeRep) (a :: TYPE r). [Char] -> a
- undefined :: forall (r :: RuntimeRep) (a :: TYPE r). HasCallStack => a
- const :: a -> b -> a
- (.) :: (b -> c) -> (a -> b) -> a -> c
- flip :: (a -> b -> c) -> b -> a -> c
- ($!) :: forall (r :: RuntimeRep) a (b :: TYPE r). (a -> b) -> a -> b
- until :: (a -> Bool) -> (a -> a) -> a -> a
- asTypeOf :: a -> a -> a
- subtract :: Num a => a -> a -> a
- maybe :: b -> (a -> b) -> Maybe a -> b
- tail :: HasCallStack => [a] -> [a]
- last :: HasCallStack => [a] -> a
- init :: HasCallStack => [a] -> [a]
- scanl :: (b -> a -> b) -> b -> [a] -> [b]
- scanl1 :: (a -> a -> a) -> [a] -> [a]
- scanr :: (a -> b -> b) -> b -> [a] -> [b]
- scanr1 :: (a -> a -> a) -> [a] -> [a]
- iterate :: (a -> a) -> a -> [a]
- repeat :: a -> [a]
- replicate :: Int -> a -> [a]
- takeWhile :: (a -> Bool) -> [a] -> [a]
- dropWhile :: (a -> Bool) -> [a] -> [a]
- take :: Int -> [a] -> [a]
- drop :: Int -> [a] -> [a]
- splitAt :: Int -> [a] -> ([a], [a])
- span :: (a -> Bool) -> [a] -> ([a], [a])
- break :: (a -> Bool) -> [a] -> ([a], [a])
- reverse :: [a] -> [a]
- and :: Foldable t => t Bool -> Bool
- or :: Foldable t => t Bool -> Bool
- any :: Foldable t => (a -> Bool) -> t a -> Bool
- all :: Foldable t => (a -> Bool) -> t a -> Bool
- notElem :: (Foldable t, Eq a) => a -> t a -> Bool
- lookup :: Eq a => a -> [(a, b)] -> Maybe b
- concatMap :: Foldable t => (a -> [b]) -> t a -> [b]
- (!!) :: HasCallStack => [a] -> Int -> a
- zip3 :: [a] -> [b] -> [c] -> [(a, b, c)]
- unzip3 :: [(a, b, c)] -> ([a], [b], [c])
- shows :: Show a => a -> ShowS
- showChar :: Char -> ShowS
- showString :: String -> ShowS
- showParen :: Bool -> ShowS -> ShowS
- odd :: Integral a => a -> Bool
- (^^) :: (Fractional a, Integral b) => a -> b -> a
- gcd :: Integral a => a -> a -> a
- lcm :: Integral a => a -> a -> a
- snd :: (a, b) -> b
- curry :: ((a, b) -> c) -> a -> b -> c
- lex :: ReadS String
- readParen :: Bool -> ReadS a -> ReadS a
- either :: (a -> c) -> (b -> c) -> Either a b -> c
- reads :: Read a => ReadS a
- read :: Read a => String -> a
- sequence_ :: (Foldable t, Monad m) => t (m a) -> m ()
- lines :: String -> [String]
- unlines :: [String] -> String
- words :: String -> [String]
- unwords :: [String] -> String
- userError :: String -> IOError
- ioError :: IOError -> IO a
- putChar :: Char -> IO ()
- putStr :: String -> IO ()
- getChar :: IO Char
- getContents :: IO String
- interact :: (String -> String) -> IO ()
- readFile :: FilePath -> IO String
- appendFile :: FilePath -> String -> IO ()
- readLn :: Read a => IO a
- readIO :: Read a => String -> IO a
Documentation
The class of semigroups (types with an associative binary operation).
Instances should satisfy the following:
You can alternatively define sconcat
instead of (<>
), in which case the
laws are:
Since: base-4.9.0.0
(<>) :: a -> a -> a infixr 6 #
An associative operation.
>>>
[1,2,3] <> [4,5,6]
[1,2,3,4,5,6]
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 =
or stimesIdempotent
stimes =
respectively.stimesIdempotentMonoid
>>>
stimes 4 [1]
[1,1,1,1]
Instances
class Monad m => MonadFail (m :: Type -> Type) #
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
Instances
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
Bits Int | Since: base-2.1 |
Defined in GHC.Bits | |
FiniteBits Int | Since: base-4.6.0.0 |
Defined in GHC.Bits | |
Bounded Int | Since: base-2.1 |
Enum Int | Since: base-2.1 |
Num Int | Since: base-2.1 |
Read Int | Since: base-2.1 |
Integral Int | Since: base-2.0.1 |
Real Int | Since: base-2.0.1 |
Defined in GHC.Real toRational :: Int -> Rational # | |
Show Int | Since: base-2.1 |
PrintfArg Int | Since: base-2.1 |
Defined in Text.Printf formatArg :: Int -> FieldFormatter # parseFormat :: Int -> ModifierParser # | |
NFData Int | |
Defined in Control.DeepSeq | |
Eq Int | |
Ord Int | |
Hashable Int | |
Defined in Data.Hashable.Class | |
Random Int | |
Uniform Int | |
Defined in System.Random.Internal uniformM :: StatefulGen g m => g -> m Int # | |
UniformRange Int | |
Defined in System.Random.Internal | |
Pretty Int | |
Defined in Text.PrettyPrint.Annotated.WL | |
Lift Int | |
Generic1 (URec Int :: k -> Type) | |
Foldable (UInt :: Type -> Type) | Since: base-4.9.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> UInt a -> Bool # maximum :: Ord a => UInt a -> a # | |
Traversable (UInt :: Type -> Type) | Since: base-4.9.0.0 |
Functor (URec Int :: Type -> Type) | Since: base-4.9.0.0 |
Generic (URec Int p) | |
Show (URec Int p) | Since: base-4.9.0.0 |
Eq (URec Int p) | Since: base-4.9.0.0 |
Ord (URec Int p) | Since: base-4.9.0.0 |
data URec Int (p :: k) | Used for marking occurrences of Since: base-4.9.0.0 |
type Rep1 (URec Int :: k -> Type) | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
type Rep (URec Int p) | Since: base-4.9.0.0 |
Defined in GHC.Generics |
Instances
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
Bounded Char | Since: base-2.1 |
Enum Char | Since: base-2.1 |
Read Char | Since: base-2.1 |
Show Char | Since: base-2.1 |
IsChar Char | Since: base-2.1 |
PrintfArg Char | Since: base-2.1 |
Defined in Text.Printf formatArg :: Char -> FieldFormatter # parseFormat :: Char -> ModifierParser # | |
Outputable String | |
Defined in System.Console.Concurrent.Internal | |
ToRegionContent String | |
Defined in System.Console.Regions toRegionContent :: String -> RegionContent # | |
NFData Char | |
Defined in Control.DeepSeq | |
Eq Char | |
Ord Char | |
Hashable Char | |
Defined in Data.Hashable.Class | |
Random Char | |
Uniform Char | |
Defined in System.Random.Internal uniformM :: StatefulGen g m => g -> m Char # | |
UniformRange Char | |
Defined in System.Random.Internal | |
Pretty Char | |
Defined in Text.PrettyPrint.Annotated.WL | |
Lift Char | |
Generic1 (URec Char :: k -> Type) | |
Foldable (UChar :: Type -> Type) | Since: base-4.9.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> UChar a -> Bool # maximum :: Ord a => UChar a -> a # minimum :: Ord a => UChar a -> a # | |
Traversable (UChar :: Type -> Type) | Since: base-4.9.0.0 |
Functor (URec Char :: Type -> Type) | Since: base-4.9.0.0 |
Generic (URec Char p) | |
Show (URec Char p) | Since: base-4.9.0.0 |
Eq (URec Char p) | Since: base-4.9.0.0 |
Ord (URec Char p) | Since: base-4.9.0.0 |
data URec Char (p :: k) | Used for marking occurrences of Since: base-4.9.0.0 |
type Compare (a :: Char) (b :: Char) | |
Defined in Data.Type.Ord | |
type Rep1 (URec Char :: k -> Type) | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
type Rep (URec Char p) | Since: base-4.9.0.0 |
Defined in GHC.Generics |
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
Floating Double | Since: base-2.1 |
RealFloat Double | Since: base-2.1 |
Defined in GHC.Float floatRadix :: Double -> Integer # floatDigits :: Double -> Int # floatRange :: Double -> (Int, Int) # decodeFloat :: Double -> (Integer, Int) # encodeFloat :: Integer -> Int -> Double # significand :: Double -> Double # scaleFloat :: Int -> Double -> Double # isInfinite :: Double -> Bool # isDenormalized :: Double -> Bool # isNegativeZero :: Double -> Bool # | |
Read Double | Since: base-2.1 |
PrintfArg Double | Since: base-2.1 |
Defined in Text.Printf formatArg :: Double -> FieldFormatter # parseFormat :: Double -> ModifierParser # | |
NFData Double | |
Defined in Control.DeepSeq | |
Erf Double | |
InvErf Double | |
Eq Double | Note that due to the presence of
Also note that
|
Ord Double | Note that due to the presence of
Also note that, due to the same,
|
Hashable Double | Note: prior to The Since: hashable-1.3.0.0 |
Defined in Data.Hashable.Class | |
Random Double | Note - |
UniformRange Double | |
Defined in System.Random.Internal | |
Pretty Double | |
Defined in Text.PrettyPrint.Annotated.WL | |
Lift Double | |
Generic1 (URec Double :: k -> Type) | |
Foldable (UDouble :: Type -> Type) | Since: base-4.9.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> UDouble a -> Bool # maximum :: Ord a => UDouble a -> a # minimum :: Ord a => UDouble a -> a # | |
Traversable (UDouble :: Type -> Type) | Since: base-4.9.0.0 |
Functor (URec Double :: Type -> Type) | Since: base-4.9.0.0 |
Generic (URec Double p) | |
Show (URec Double p) | Since: base-4.9.0.0 |
Eq (URec Double p) | Since: base-4.9.0.0 |
Ord (URec Double p) | Since: base-4.9.0.0 |
Defined in GHC.Generics 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 # | |
data URec Double (p :: k) | Used for marking occurrences of Since: base-4.9.0.0 |
type Rep1 (URec Double :: k -> Type) | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
type Rep (URec Double p) | Since: base-4.9.0.0 |
Defined in GHC.Generics |
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
Floating Float | Since: base-2.1 |
RealFloat Float | Since: base-2.1 |
Defined in GHC.Float floatRadix :: Float -> Integer # floatDigits :: Float -> Int # floatRange :: Float -> (Int, Int) # decodeFloat :: Float -> (Integer, Int) # encodeFloat :: Integer -> Int -> Float # significand :: Float -> Float # scaleFloat :: Int -> Float -> Float # isInfinite :: Float -> Bool # isDenormalized :: Float -> Bool # isNegativeZero :: Float -> Bool # | |
Read Float | Since: base-2.1 |
PrintfArg Float | Since: base-2.1 |
Defined in Text.Printf formatArg :: Float -> FieldFormatter # parseFormat :: Float -> ModifierParser # | |
NFData Float | |
Defined in Control.DeepSeq | |
Erf Float | |
InvErf Float | |
Eq Float | Note that due to the presence of
Also note that
|
Ord Float | Note that due to the presence of
Also note that, due to the same,
|
Hashable Float | Note: prior to The Since: hashable-1.3.0.0 |
Defined in Data.Hashable.Class | |
Random Float | Note - |
UniformRange Float | |
Defined in System.Random.Internal | |
Pretty Float | |
Defined in Text.PrettyPrint.Annotated.WL | |
Lift Float | |
Generic1 (URec Float :: k -> Type) | |
Foldable (UFloat :: Type -> Type) | Since: base-4.9.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> UFloat a -> Bool # maximum :: Ord a => UFloat a -> a # minimum :: Ord a => UFloat a -> a # | |
Traversable (UFloat :: Type -> Type) | Since: base-4.9.0.0 |
Functor (URec Float :: Type -> Type) | Since: base-4.9.0.0 |
Generic (URec Float p) | |
Show (URec Float p) | |
Eq (URec Float p) | |
Ord (URec Float p) | |
Defined in GHC.Generics | |
data URec Float (p :: k) | Used for marking occurrences of Since: base-4.9.0.0 |
type Rep1 (URec Float :: k -> Type) | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
type Rep (URec Float p) | |
Defined in GHC.Generics |
Instances
Bits Word | Since: base-2.1 |
Defined in GHC.Bits (.&.) :: Word -> Word -> Word # (.|.) :: Word -> Word -> Word # complement :: Word -> Word # shift :: Word -> Int -> Word # rotate :: Word -> Int -> Word # setBit :: Word -> Int -> Word # clearBit :: Word -> Int -> Word # complementBit :: Word -> Int -> Word # testBit :: Word -> Int -> Bool # bitSizeMaybe :: Word -> Maybe Int # shiftL :: Word -> Int -> Word # unsafeShiftL :: Word -> Int -> Word # shiftR :: Word -> Int -> Word # unsafeShiftR :: Word -> Int -> Word # rotateL :: Word -> Int -> Word # | |
FiniteBits Word | Since: base-4.6.0.0 |
Defined in GHC.Bits | |
Bounded Word | Since: base-2.1 |
Enum Word | Since: base-2.1 |
Num Word | Since: base-2.1 |
Read Word | Since: base-4.5.0.0 |
Integral Word | Since: base-2.1 |
Real Word | Since: base-2.1 |
Defined in GHC.Real toRational :: Word -> Rational # | |
Show Word | Since: base-2.1 |
PrintfArg Word | Since: base-2.1 |
Defined in Text.Printf formatArg :: Word -> FieldFormatter # parseFormat :: Word -> ModifierParser # | |
NFData Word | |
Defined in Control.DeepSeq | |
Eq Word | |
Ord Word | |
Hashable Word | |
Defined in Data.Hashable.Class | |
Random Word | |
Uniform Word | |
Defined in System.Random.Internal uniformM :: StatefulGen g m => g -> m Word # | |
UniformRange Word | |
Defined in System.Random.Internal | |
Pretty Word | |
Defined in Text.PrettyPrint.Annotated.WL | |
Lift Word | |
Generic1 (URec Word :: k -> Type) | |
Foldable (UWord :: Type -> Type) | Since: base-4.9.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> UWord a -> Bool # maximum :: Ord a => UWord a -> a # minimum :: Ord a => UWord a -> a # | |
Traversable (UWord :: Type -> Type) | Since: base-4.9.0.0 |
Functor (URec Word :: Type -> Type) | Since: base-4.9.0.0 |
Generic (URec Word p) | |
Show (URec Word p) | Since: base-4.9.0.0 |
Eq (URec Word p) | Since: base-4.9.0.0 |
Ord (URec Word p) | Since: base-4.9.0.0 |
data URec Word (p :: k) | Used for marking occurrences of Since: base-4.9.0.0 |
type Rep1 (URec Word :: k -> Type) | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
type Rep (URec Word p) | Since: base-4.9.0.0 |
Defined in GHC.Generics |
Instances
Monoid Ordering | Since: base-2.1 |
Semigroup Ordering | Since: base-4.9.0.0 |
Bounded Ordering | Since: base-2.1 |
Enum Ordering | Since: base-2.1 |
Generic Ordering | |
Read Ordering | Since: base-2.1 |
Show Ordering | Since: base-2.1 |
NFData Ordering | |
Defined in Control.DeepSeq | |
Eq Ordering | |
Ord Ordering | |
Defined in GHC.Classes | |
Hashable Ordering | |
Defined in Data.Hashable.Class | |
type Rep Ordering | Since: base-4.6.0.0 |
The Maybe
type encapsulates an optional value. A value of type
either contains a value of type Maybe
aa
(represented as
),
or it is empty (represented as Just
aNothing
). 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.
Instances
MonadFail Maybe | Since: base-4.9.0.0 |
Defined in Control.Monad.Fail | |
MonadZip Maybe | Since: base-4.8.0.0 |
Foldable Maybe | Since: base-2.1 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> Maybe a -> Bool # maximum :: Ord a => Maybe a -> a # minimum :: Ord a => Maybe a -> a # | |
Eq1 Maybe | Since: base-4.9.0.0 |
Ord1 Maybe | Since: base-4.9.0.0 |
Defined in Data.Functor.Classes | |
Read1 Maybe | Since: base-4.9.0.0 |
Defined in Data.Functor.Classes | |
Show1 Maybe | Since: base-4.9.0.0 |
Traversable Maybe | Since: base-2.1 |
Alternative Maybe | Picks the leftmost Since: base-2.1 |
Applicative Maybe | Since: base-2.1 |
Functor Maybe | Since: base-2.1 |
Monad Maybe | Since: base-2.1 |
MonadPlus Maybe | Picks the leftmost Since: base-2.1 |
NFData1 Maybe | Since: deepseq-1.4.3.0 |
Defined in Control.DeepSeq | |
MonadThrow Maybe | |
Defined in Control.Monad.Catch throwM :: (HasCallStack, Exception e) => e -> Maybe a # | |
Hashable1 Maybe | |
Defined in Data.Hashable.Class | |
Generic1 Maybe | |
MonadBaseControl Maybe Maybe | |
MonadError () Maybe | Since: mtl-2.2.2 |
Defined in Control.Monad.Error.Class throwError :: () -> Maybe a # catchError :: Maybe a -> (() -> Maybe a) -> Maybe a # | |
MonadBase Maybe Maybe | |
Defined in Control.Monad.Base | |
Lift a => Lift (Maybe a :: Type) | |
Semigroup a => Monoid (Maybe a) | Lift a semigroup into Since 4.11.0: constraint on inner Since: base-2.1 |
Semigroup a => Semigroup (Maybe a) | Since: base-4.9.0.0 |
Generic (Maybe a) | |
SingKind a => SingKind (Maybe a) | Since: base-4.9.0.0 |
Defined in GHC.Generics type DemoteRep (Maybe a) | |
Read a => Read (Maybe a) | Since: base-2.1 |
Show a => Show (Maybe a) | Since: base-2.1 |
NFData a => NFData (Maybe a) | |
Defined in Control.DeepSeq | |
Eq a => Eq (Maybe a) | Since: base-2.1 |
Ord a => Ord (Maybe a) | Since: base-2.1 |
Hashable a => Hashable (Maybe a) | |
Defined in Data.Hashable.Class | |
Pretty a => Pretty (Maybe a) | |
Defined in Text.PrettyPrint.Annotated.WL | |
SingI ('Nothing :: Maybe a) | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
SingI a2 => SingI ('Just a2 :: Maybe a1) | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
type Rep1 Maybe | Since: base-4.6.0.0 |
type StM Maybe a | |
Defined in Control.Monad.Trans.Control | |
type DemoteRep (Maybe a) | |
Defined in GHC.Generics | |
type Rep (Maybe a) | Since: base-4.6.0.0 |
Defined in GHC.Generics | |
data Sing (b :: Maybe a) | |
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.
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
A value of type
is a computation which, when performed,
does some I/O before returning a value of type IO
aa
.
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
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)<>
zSemigroup
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 newtype
s and make those instances
of Monoid
, e.g. Sum
and Product
.
NOTE: Semigroup
is a superclass of Monoid
since base-4.11.0.0.
Identity of mappend
>>>
"Hello world" <> mempty
"Hello world"
An associative operation
NOTE: This method is redundant and has the default
implementation
since base-4.11.0.0.
Should it be implemented manually, since mappend
= (<>
)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
.
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
Monoid ByteArray | Since: base-4.17.0.0 |
Monoid All | Since: base-2.1 |
Monoid Any | Since: base-2.1 |
Monoid Builder | |
Monoid ByteString | |
Defined in Data.ByteString.Internal.Type mempty :: ByteString # mappend :: ByteString -> ByteString -> ByteString # mconcat :: [ByteString] -> ByteString # | |
Monoid ByteString | |
Defined in Data.ByteString.Lazy.Internal mempty :: ByteString # mappend :: ByteString -> ByteString -> ByteString # mconcat :: [ByteString] -> ByteString # | |
Monoid ShortByteString | |
Defined in Data.ByteString.Short.Internal mappend :: ShortByteString -> ShortByteString -> ShortByteString # mconcat :: [ShortByteString] -> ShortByteString # | |
Monoid IntSet | |
Monoid Ordering | Since: base-2.1 |
Monoid Cover Source # | |
Monoid CoverCount Source # | |
Defined in Hedgehog.Internal.Property mempty :: CoverCount # mappend :: CoverCount -> CoverCount -> CoverCount # mconcat :: [CoverCount] -> CoverCount # | |
Monoid Journal Source # | |
Monoid LabelName Source # | |
Monoid Summary Source # | |
Monoid OsString | "String-Concatenation" for |
Monoid PosixString | |
Defined in System.OsString.Internal.Types mempty :: PosixString # mappend :: PosixString -> PosixString -> PosixString # mconcat :: [PosixString] -> PosixString # | |
Monoid WindowsString | |
Defined in System.OsString.Internal.Types mempty :: WindowsString # mappend :: WindowsString -> WindowsString -> WindowsString # mconcat :: [WindowsString] -> WindowsString # | |
Monoid Doc | |
Monoid () | Since: base-2.1 |
(Semigroup a, Monoid a) => Monoid (Concurrently a) | Since: async-2.1.0 |
Defined in Control.Concurrent.Async.Internal mempty :: Concurrently a # mappend :: Concurrently a -> Concurrently a -> Concurrently a # mconcat :: [Concurrently a] -> Concurrently a # | |
FiniteBits a => Monoid (And a) | This constraint is arguably too strong. However,
as some types (such as Since: base-4.16 |
FiniteBits a => Monoid (Iff a) | This constraint is arguably
too strong. However, as some types (such as Since: base-4.16 |
Bits a => Monoid (Ior a) | Since: base-4.16 |
Bits a => Monoid (Xor a) | Since: base-4.16 |
Monoid a => Monoid (Identity a) | Since: base-4.9.0.0 |
Ord a => Monoid (Max a) | Since: base-4.8.0.0 |
Ord a => Monoid (Min a) | Since: base-4.8.0.0 |
Monoid (First a) | Since: base-2.1 |
Monoid (Last a) | Since: base-2.1 |
Monoid a => Monoid (Down a) | Since: base-4.11.0.0 |
(Ord a, Bounded a) => Monoid (Max a) | Since: base-4.9.0.0 |
(Ord a, Bounded a) => Monoid (Min a) | Since: base-4.9.0.0 |
Monoid m => Monoid (WrappedMonoid m) | Since: base-4.9.0.0 |
Defined in Data.Semigroup mempty :: WrappedMonoid m # mappend :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m # mconcat :: [WrappedMonoid m] -> WrappedMonoid m # | |
Monoid a => Monoid (Dual a) | Since: base-2.1 |
Monoid (Endo a) | Since: base-2.1 |
Num a => Monoid (Product a) | Since: base-2.1 |
Num a => Monoid (Sum a) | Since: base-2.1 |
Monoid a => Monoid (STM a) | Since: base-4.17.0.0 |
(Generic a, Monoid (Rep a ())) => Monoid (Generically a) | Since: base-4.17.0.0 |
Defined in GHC.Generics mempty :: Generically a # mappend :: Generically a -> Generically a -> Generically a # mconcat :: [Generically a] -> Generically a # | |
Monoid p => Monoid (Par1 p) | Since: base-4.12.0.0 |
Num a => Monoid (AlphaColour a) | |
Defined in Data.Colour.Internal mempty :: AlphaColour a # mappend :: AlphaColour a -> AlphaColour a -> AlphaColour a # mconcat :: [AlphaColour a] -> AlphaColour a # | |
Num a => Monoid (Colour a) | |
Monoid (IntMap a) | |
Monoid (Seq a) | |
Monoid (MergeSet a) | |
Ord a => Monoid (Set a) | |
Monoid a => Monoid (IO a) | Since: base-4.9.0.0 |
(Semigroup a, Monoid a) => Monoid (Coverage a) Source # | |
Monoid (Doc a) | |
Monoid a => Monoid (Q a) | Since: template-haskell-2.17.0.0 |
Monoid (Doc a) | |
Semigroup a => Monoid (Maybe a) | Lift a semigroup into Since 4.11.0: constraint on inner Since: base-2.1 |
Monoid a => Monoid (a) | Since: base-4.15 |
Monoid [a] | Since: base-2.1 |
(Semigroup a, Monoid a) => Monoid (ConcurrentlyE e a) | |
Defined in Control.Concurrent.Async.Internal mempty :: ConcurrentlyE e a # mappend :: ConcurrentlyE e a -> ConcurrentlyE e a -> ConcurrentlyE e a # mconcat :: [ConcurrentlyE e a] -> ConcurrentlyE e a # | |
Monoid (Proxy s) | Since: base-4.7.0.0 |
Monoid (U1 p) | Since: base-4.12.0.0 |
Monoid a => Monoid (ST s a) | Since: base-4.11.0.0 |
Ord k => Monoid (Map k v) | |
(Monad m, Monoid a) => Monoid (GenT m a) Source # | |
(MonadBaseControl IO m, Semigroup a, Monoid a) => Monoid (Concurrently m a) | |
Defined in Control.Concurrent.Async.Lifted mempty :: Concurrently m a # mappend :: Concurrently m a -> Concurrently m a -> Concurrently m a # mconcat :: [Concurrently m a] -> Concurrently m a # | |
(Monoid a, Monoid b) => Monoid (a, b) | Since: base-2.1 |
Monoid b => Monoid (a -> b) | Since: base-2.1 |
Monoid a => Monoid (Const a b) | Since: base-4.9.0.0 |
(Applicative f, Monoid a) => Monoid (Ap f a) | Since: base-4.12.0.0 |
Alternative f => Monoid (Alt f a) | Since: base-4.8.0.0 |
Monoid (f p) => Monoid (Rec1 f p) | Since: base-4.12.0.0 |
(Semigroup a, Monoid a) => Monoid (Tagged s a) | |
Monoid a => Monoid (Constant a b) | |
(Monoid a, Monoid b, Monoid c) => Monoid (a, b, c) | Since: base-2.1 |
(Monoid (f a), Monoid (g a)) => Monoid (Product f g a) | Since: base-4.16.0.0 |
(Monoid (f p), Monoid (g p)) => Monoid ((f :*: g) p) | Since: base-4.12.0.0 |
Monoid c => Monoid (K1 i c p) | Since: base-4.12.0.0 |
(Monoid a, Monoid b, Monoid c, Monoid d) => Monoid (a, b, c, d) | Since: base-2.1 |
Monoid (f (g a)) => Monoid (Compose f g a) | Since: base-4.16.0.0 |
Monoid (f (g p)) => Monoid ((f :.: g) p) | Since: base-4.12.0.0 |
Monoid (f p) => Monoid (M1 i c f p) | Since: base-4.12.0.0 |
(Monoid a, Monoid b, Monoid c, Monoid d, Monoid e) => Monoid (a, b, c, d, e) | Since: base-2.1 |
The class of semigroups (types with an associative binary operation).
Instances should satisfy the following:
You can alternatively define sconcat
instead of (<>
), in which case the
laws are:
Since: base-4.9.0.0