| Stability | experimental |
|---|---|
| Maintainer | ekmett@gmail.com |
| Safe Haskell | None |
Data.Functor.Contravariant.Representable
Contents
Description
Representable contravariant endofunctors over the category of Haskell
types are isomorphic to (_ -> r) and resemble mappings to a
fixed range.
- type family Value f
- class Contravariant f => Valued f where
- contramapWithValue :: (b -> Either a (Value f)) -> f a -> f b
- class Coindexed f where
- class (Coindexed f, Valued f) => Representable f where
- contramapDefault :: Representable f => (a -> b) -> f b -> f a
- contramapWithValueDefault :: Representable f => (b -> Either a (Value f)) -> f a -> f b
Values
Contravariant Keyed
class Contravariant f => Valued f whereSource
Dual to Keyed.
Methods
contramapWithValue :: (b -> Either a (Value f)) -> f a -> f bSource
Contravariant Indexed
Dual to Indexed.
Representable Contravariant Functors
class (Coindexed f, Valued f) => Representable f whereSource
A Contravariant functor f is Representable if contrarep and coindex witness an isomorphism to (_ -> Value f).
Instances
| Representable Predicate | |
| Representable (Op r) | |
| (Representable f, Representable g) => Representable (Day f g) | |
| (Representable f, Representable g) => Representable (Product f g) |
Default definitions
contramapDefault :: Representable f => (a -> b) -> f b -> f aSource
contramapWithValueDefault :: Representable f => (b -> Either a (Value f)) -> f a -> f bSource