{-# LANGUAGE ExplicitForAll #-}
{-# LANGUAGE KindSignatures #-}

-- | Functor of Functors
module Data.FFunctor where

class FFunctor (f :: (* -> *) -> *) where
--ffmap :: (Functor m, Functor n) => (m ~> n) -> f m -> f n
  ffmap :: forall m n a . (Functor m, Functor n) => (m a -> n a) -> f m -> f n

-- TODO is there anything from stdlib that could have an instance?