Control.Flower.Functor.Lazy

Documentation

lift :: Functor f => (a -> b) -> f a -> f b

Rename fmap to lift for consistency

>>> lift (+1) <| Just 0
Just 1

>>> lift (lift (+1)) [[1,2,3],[4,5,6]]
[[2,3,4],[5,6,7]]

over :: (a -> b) -> a -> b

Alias for apply, for readability (especially when teaching)

>>> lift (+1) `over` Just 0
Just 1

>>> Just 0 $> (+1) $> (+2)
Just 3

>>> (*2) <$ ([1,2,3] $> (+1))
[4,6,8]

>>> (+8) .> (*2) <$ Just 0
Just 16

>>> (*3) <. (+8) <$ Just 0
Just 24

(<$) :: Functor f => (a -> b) -> f a -> f b infixr 4

Operator for lift highlighting the direction of data flow

>>> (+1) <$ Just 0
Just 1

>>> (+2) <$ (+1) <$ Just 0
Just 3

>>> ((*2) <$ [1,2,3]) $> (+1)
[3,5,7]

>>> Just 0 $> (+8) .> (*2)
Just 16

>>> Just 0 $> (*3) <. (+8)
Just 24

($>) :: Functor f => f a -> (a -> b) -> f b infixl 4

Operator for lift highlighting the reversed direction of data flow

>>> Just 0 $> (+1)
Just 1