Safe Haskell | None |
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- class (Contravariant f, Corepresentable g) => Adjunction f g | f -> g, g -> f where
- unit :: a -> g (f a)
- counit :: a -> f (g a)
- leftAdjunct :: (b -> f a) -> a -> g b
- rightAdjunct :: (a -> g b) -> b -> f a

- corepAdjunction :: Adjunction f g => (a -> f ()) -> g a
- coindexAdjunction :: Adjunction f g => g a -> a -> f ()

# Documentation

class (Contravariant f, Corepresentable g) => Adjunction f g | f -> g, g -> f whereSource

An adjunction from Hask^op to Hask

Op (f a) b ~ Hask a (g b)

rightAdjunct unit = id leftAdjunct counit = id

Any adjunction from Hask to Hask^op would indirectly permit unsafePerformIO, and therefore does not exist.

leftAdjunct :: (b -> f a) -> a -> g bSource

rightAdjunct :: (a -> g b) -> b -> f aSource

Adjunction Predicate Predicate | This gives rise to the Cont Bool monad |

Adjunction (Op r) (Op r) | This adjunction gives rise to the Cont monad |

corepAdjunction :: Adjunction f g => (a -> f ()) -> g aSource

Represent a contravariant functor that has a left adjoint

coindexAdjunction :: Adjunction f g => g a -> a -> f ()Source