|
|
|
|
|
|
by Iceland_jack
1237 days ago
|
|
|
Either a :: Type -> Type
is a Haskell Functor (endofunctor), mapping (->) to (->). Either :: Type -> (Type -> Type)
is not an endofunctor, it maps a type to a type constructor and thus maps (->) to (~>) (natural transformations).If you uncurried Either, you would also get a non-endofunctor which maps from (-×>) (product category) to (->). Either' :: (Type, Type) -> Type
Every function is a functor between equality, since equality satisfies congruence: isPrime :: Integer -> Bool
is a functor between (:~:) @Integer an (:~:) @Bool.
Boolean negation is a function between "less than or equal" to "greater than or equal" categories; mapping (<=) to (>=): not :: Bool -> Bool
|
|
|