Tetramputechture

newtype Combine a b =
  Combine { unCombine :: (a -> b) }
-- example usage
-- > let f = Combine $ \n -> Sum (n + 1)
-- > unCombine f $ 1
-- 2

-- dummy show instance so quickCheck works
instance Show (Combine a b) where
  show (Combine f) = "Combine instance"