| Safe Haskell | None |
|---|
Data.Functor.Contravariant.Adjunction
- 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.
Instances
| 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