MHask.Functor

Compare to base.Prelude.Functor (Functor)

Documentation

class Functor t where

Functor is its own dual.

Methods

fmap :: (Monad m, Monad n) => (m ~> n) -> t m ~> t n

Flipping the arrows on fmap's type signature is just the same type signature in disguise.

 (m <~ n) -> (t m <~ t n)

Instances

Functor (WriterT w)

Functor (StateT s)

Functor (ReaderT r)