{-# LANGUAGE InstanceSigs, KindSignatures #-}

class Monoid' a where
  mempty' :: a
  mappend' :: a -> a -> a

instance Monoid' [a] where
  mempty' :: [a]
  mempty' = []

  mappend' :: [a] -> [a] -> [a]
  mappend' x y = x ++ y


class Functor (f :: * -> *) where
  fmap :: (a -> b) -> (f a -> f b)