Safe Haskell	None
Language	Haskell2010

Lens.Labels

Contents

Lenses
HasLens
Setters
Getters

Description

A lens library that integrates with OverloadedLabels.

Unlike the lens package (and others), lenses are defined as a newtype instead of a type synonym, to avoid overlapping with other IsLabel instances. However, the LensFn and runLens functions allow converting between the two types; for example:

LensFn :: Control.Lens.LensLike f s t a b -> Lens.Labels.LensLike f s t a b
runLens :: Lens.Labels.LensLike f s t a b -> Control.Lens.LensLike f s t a b

TODO: support more general optic types (e.g., prisms).

Synopsis

newtype LensFn a b = LensFn {
- runLens :: a -> b
}
type LensLike f s t a b = LensFn (a -> f b) (s -> f t)
type LensLike' f s a = LensLike f s s a a
(&) :: a -> (a -> b) -> b
(.) :: Category cat => cat b c -> cat a b -> cat a c
type Lens s t a b = forall f. Functor f => LensLike f s t a b
type Lens' s a = Lens s s a a
class HasLens f s t (x :: Symbol) a b | x s -> a, x t -> b, x s b -> t, x t a -> s where
data Proxy# :: forall k0. k0 -> TYPE (TupleRep ([] :: [RuntimeRep]))
proxy# :: Proxy# a
class HasLens f s s x a a => HasLens' f s x a | x s -> a where
type ASetter s t a b = LensLike Identity s t a b
(.~) :: ASetter s t a b -> b -> s -> t
(%~) :: ASetter s t a b -> (a -> b) -> s -> t
set :: ASetter s t a b -> b -> s -> t
over :: ASetter s t a b -> (a -> b) -> s -> t
newtype Const a (b :: k) :: forall k. * -> k -> * = Const {
- getConst :: a
}
type Getting r s t a b = LensLike (Const r) s t a b
(^.) :: s -> Getting a s t a b -> a
view :: Getting a s t a b -> s -> a

Lenses

newtype LensFn a b Source #

A newtype for defining lenses. Can be composed using '(Control.Category..)', which is exported from this module.

Constructors

LensFn
Fields runLens :: a -> b

Instances

(p ~ (a -> f b), q ~ (s -> f t), HasLens f s t x a b) => IsLabel x (LensFn p q) Source #
Instance details Defined in Lens.Labels Methods fromLabel :: LensFn p q #
Category LensFn Source #
Instance details Defined in Lens.Labels Methods id :: LensFn a a # (.) :: LensFn b c -> LensFn a b -> LensFn a c #

type LensLike f s t a b = LensFn (a -> f b) (s -> f t) Source #

type LensLike' f s a = LensLike f s s a a Source #

(&) :: 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

(.) :: Category cat => cat b c -> cat a b -> cat a c infixr 9 #

morphism composition

type Lens s t a b = forall f. Functor f => LensLike f s t a b Source #

type Lens' s a = Lens s s a a Source #

HasLens

class HasLens f s t (x :: Symbol) a b | x s -> a, x t -> b, x s b -> t, x t a -> s where Source #

A type class for lens fields.

Minimal complete definition

lensOf

Methods

lensOf :: Proxy# x -> (a -> f b) -> s -> f t Source #

data Proxy# :: forall k0. k0 -> TYPE (TupleRep ([] :: [RuntimeRep])) #

The type constructor Proxy# is used to bear witness to some type variable. It's used when you want to pass around proxy values for doing things like modelling type applications. A Proxy# is not only unboxed, it also has a polymorphic kind, and has no runtime representation, being totally free.

proxy# :: Proxy# a #

Witness for an unboxed Proxy# value, which has no runtime representation.

class HasLens f s s x a a => HasLens' f s x a | x s -> a where Source #

A type class for lens fields of monomorphic types (i.e., where the lens doesn't change the outer type).

This class can be used to simplify instance declarations and type errors, by "forwarding" HasLens to simpler instances. For example:

    instance (HasLens' f Foo x a, a ~ b) => HasLens f Foo Foo x a b where
        where lensOf = lensOf'
    instance Functor f => HasLens' f Foo "a" Int where ...
    instance Functor f => HasLens' f Foo "b" Double where ...
    instance Functor f => HasLens' f Foo "c" [Float]  where ...
    ...

Minimal complete definition

lensOf'

Methods

lensOf' :: Proxy# x -> (a -> f a) -> s -> f s Source #

Setters

type ASetter s t a b = LensLike Identity s t a b Source #

(.~) :: ASetter s t a b -> b -> s -> t infixr 4 Source #

(%~) :: ASetter s t a b -> (a -> b) -> s -> t infixr 4 Source #

set :: ASetter s t a b -> b -> s -> t Source #

over :: ASetter s t a b -> (a -> b) -> s -> t Source #

Getters

newtype Const a (b :: k) :: forall k. * -> k -> * #

The Const functor.

Constructors

Const
Fields getConst :: a

Instances

Generic1 (Const a :: k -> *)
Instance details Defined in Data.Functor.Const Associated Types type Rep1 (Const a) :: k -> * # Methods from1 :: Const a a0 -> Rep1 (Const a) a0 # to1 :: Rep1 (Const a) a0 -> Const a a0 #
Functor (Const m :: * -> *)	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 #
Monoid m => Applicative (Const m :: * -> *)	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 #
Foldable (Const m :: * -> *)	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 # 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 #
Traversable (Const m :: * -> *)	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) #
Bounded a => Bounded (Const a b)
Instance details Defined in Data.Functor.Const Methods minBound :: Const a b # maxBound :: Const a b #
Enum a => Enum (Const a b)
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] #
Eq a => Eq (Const a b)
Instance details Defined in Data.Functor.Const Methods (==) :: Const a b -> Const a b -> Bool # (/=) :: Const a b -> Const a b -> Bool #
Floating a => Floating (Const a b)
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 #
Fractional a => Fractional (Const a b)
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 #
Integral a => Integral (Const a b)
Instance details Defined in Data.Functor.Const Methods quot :: Const a b -> Const a b -> Const a b # rem :: Const a b -> Const a b -> Const a b # div :: Const a b -> Const a b -> Const a b # mod :: Const a b -> Const a b -> Const a b # quotRem :: Const a b -> Const a b -> (Const a b, Const a b) # divMod :: Const a b -> Const a b -> (Const a b, Const a b) # toInteger :: Const a b -> Integer #
Num a => Num (Const a b)
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 #
Ord a => Ord (Const a b)
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 #
Read a => Read (Const a b)	This instance would be equivalent to the derived instances of the `Const` newtype if the `runConst` field were removed Since: base-4.8.0.0
Instance details Defined in Data.Functor.Const Methods readsPrec :: Int -> ReadS (Const a b) # readList :: ReadS [Const a b] # readPrec :: ReadPrec (Const a b) # readListPrec :: ReadPrec [Const a b] #
Real a => Real (Const a b)
Instance details Defined in Data.Functor.Const Methods toRational :: Const a b -> Rational #
RealFloat a => RealFloat (Const a b)
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 #
RealFrac a => RealFrac (Const a b)
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 #
Show a => Show (Const a b)	This instance would be equivalent to the derived instances of the `Const` newtype if the `runConst` 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 #
Ix a => Ix (Const a b)
Instance details Defined in Data.Functor.Const Methods range :: (Const a b, Const a b) -> [Const a b] # index :: (Const a b, Const a b) -> Const a b -> Int # unsafeIndex :: (Const a b, Const a b) -> Const a b -> Int inRange :: (Const a b, Const a b) -> Const a b -> Bool # rangeSize :: (Const a b, Const a b) -> Int # unsafeRangeSize :: (Const a b, Const a b) -> Int
Generic (Const a b)
Instance details Defined in Data.Functor.Const Associated Types type Rep (Const a b) :: * -> * # Methods from :: Const a b -> Rep (Const a b) x # to :: Rep (Const a b) x -> Const a b #
Semigroup a => Semigroup (Const a b)
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 #
Monoid a => Monoid (Const a b)
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 #
Storable a => Storable (Const a b)
Instance details Defined in Data.Functor.Const Methods sizeOf :: Const a b -> Int # alignment :: Const a b -> Int # peekElemOff :: Ptr (Const a b) -> Int -> IO (Const a b) # pokeElemOff :: Ptr (Const a b) -> Int -> Const a b -> IO () # peekByteOff :: Ptr b0 -> Int -> IO (Const a b) # pokeByteOff :: Ptr b0 -> Int -> Const a b -> IO () # peek :: Ptr (Const a b) -> IO (Const a b) # poke :: Ptr (Const a b) -> Const a b -> IO () #
Bits a => Bits (Const a b)
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 # xor :: Const a b -> Const a b -> Const a b # complement :: Const a b -> Const a b # shift :: Const a b -> Int -> Const a b # rotate :: Const a b -> Int -> Const a b # zeroBits :: Const a b # bit :: Int -> Const a b # setBit :: Const a b -> Int -> Const a b # clearBit :: Const a b -> Int -> Const a b # complementBit :: Const a b -> Int -> Const a b # testBit :: Const a b -> Int -> Bool # bitSizeMaybe :: Const a b -> Maybe Int # bitSize :: Const a b -> Int # isSigned :: Const a b -> Bool # shiftL :: Const a b -> Int -> Const a b # unsafeShiftL :: Const a b -> Int -> Const a b # shiftR :: Const a b -> Int -> Const a b # unsafeShiftR :: Const a b -> Int -> Const a b # rotateL :: Const a b -> Int -> Const a b # rotateR :: Const a b -> Int -> Const a b # popCount :: Const a b -> Int #
FiniteBits a => FiniteBits (Const a b)
Instance details Defined in Data.Functor.Const Methods finiteBitSize :: Const a b -> Int # countLeadingZeros :: Const a b -> Int # countTrailingZeros :: Const a b -> Int #
type Rep1 (Const a :: k -> *)
Instance details Defined in Data.Functor.Const type Rep1 (Const a :: k -> *) = D1 (MetaData "Const" "Data.Functor.Const" "base" True) (C1 (MetaCons "Const" PrefixI True) (S1 (MetaSel (Just "getConst") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a)))
type Rep (Const a b)
Instance details Defined in Data.Functor.Const type Rep (Const a b) = D1 (MetaData "Const" "Data.Functor.Const" "base" True) (C1 (MetaCons "Const" PrefixI True) (S1 (MetaSel (Just "getConst") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a)))

type Getting r s t a b = LensLike (Const r) s t a b Source #

(^.) :: s -> Getting a s t a b -> a infixl 8 Source #

view :: Getting a s t a b -> s -> a Source #