Data.Comp.Param.Difunctor

This module defines difunctors (Meijer, Hutton, FPCA '95), i.e. binary type constructors that are contravariant in the first argument and covariant in the second argument.

Documentation

difmap :: Difunctor f => (a -> b) -> f c a -> f c b

class Difunctor f where

This class represents difunctors, i.e. binary type constructors that are contravariant in the first argument and covariant in the second argument.

Methods

dimap :: (a -> b) -> (c -> d) -> f b c -> f a d

Instances

Difunctor (->)

The canonical example of a difunctor.

Difunctor f => Difunctor ((:&:) f p)

(Difunctor f, Difunctor g) => Difunctor ((:+:) f g)