Data.Bifunctor

class Bifunctor f  where

A Bifunctor is a Functor from the pair category (Type, Type) to Type.

A type constructor with two type arguments can be made into a Bifunctor if both of its type arguments are covariant.

The bimap function maps a pair of functions over the two type arguments of the bifunctor.

Laws:

• Identity: bimap identity identity == identity
• Composition: bimap f1 g1 <<< bimap f2 g2 == bimap (f1 <<< f2) (g1 <<< g2)

Members

• bimap :: forall a b c d. (a -> b) -> (c -> d) -> f a c -> f b d

Instances

• Bifunctor Either
• Bifunctor Tuple
• Bifunctor Const

lmap :: forall f a b c. Bifunctor f => (a -> b) -> f a c -> f b c

Map a function over the first type argument of a Bifunctor.

rmap :: forall f a b c. Bifunctor f => (b -> c) -> f a b -> f a c

Map a function over the second type arguments of a Bifunctor.