Data.Lens.Common

Documentation

newtype Lens a b

Constructors

Lens

Fields

runLens :: a -> Store b a

Instances

Tensor Lens

Category * Lens

Semigroupoid * Lens

Lens construction

lens :: (a -> b) -> (b -> a -> a) -> Lens a b

build a lens out of a getter and setter

iso :: (a -> b) -> (b -> a) -> Lens a b

build a lens out of an isomorphism

Functional API

getL :: Lens a b -> a -> b

Gets the getter function from a lens.

setL :: Lens a b -> b -> a -> a

Gets the setter function from a lens.

modL :: Lens a b -> (b -> b) -> a -> a

Gets the modifier function from a lens.

mergeL :: Lens a c -> Lens b c -> Lens (Either a b) c

Operator API

(^$) :: Lens a b -> a -> b infixr 0

(^$!) :: Lens a b -> a -> b infixr 0

(^.) :: a -> Lens a b -> b infixl 9

functional getter, which acts like a field accessor

(^!) :: a -> Lens a b -> b infixl 9

functional getter, which acts like a field accessor

(^=) :: Lens a b -> b -> a -> a infixr 4

(^!=) :: Lens a b -> b -> a -> a infixr 4

(^%=) :: Lens a b -> (b -> b) -> a -> a infixr 4

functional modify

(^!%=) :: Lens a b -> (b -> b) -> a -> a infixr 4

functional modify

(^%%=) :: Functor f => Lens a b -> (b -> f b) -> a -> f a infixr 4

functorial modify

Pseudo-imperatives

(^+=) :: Num b => Lens a b -> b -> a -> a infixr 4

(^!+=) :: Num b => Lens a b -> b -> a -> a infixr 4

(^-=) :: Num b => Lens a b -> b -> a -> a infixr 4

(^!-=) :: Num b => Lens a b -> b -> a -> a infixr 4

(^*=) :: Num b => Lens a b -> b -> a -> a infixr 4

(^!*=) :: Num b => Lens a b -> b -> a -> a infixr 4

(^/=) :: Fractional b => Lens a b -> b -> a -> a infixr 4

(^!/=) :: Fractional b => Lens a b -> b -> a -> a infixr 4

Stock lenses

fstLens :: Lens (a, b) a

sndLens :: Lens (a, b) b

mapLens :: Ord k => k -> Lens (Map k v) (Maybe v)

intMapLens :: Int -> Lens (IntMap v) (Maybe v)

setLens :: Ord k => k -> Lens (Set k) Bool

intSetLens :: Int -> Lens IntSet Bool