class Zip a b | b -> a where
  zipper :: [a] -> b

instance Zip a [a] where
  zipper as = as

instance Zip a b => Zip (x -> a) ([x] -> b) where
  zipper fs as = zipper (zipWith ($) fs as)

generalZipWith :: Zip a b => a -> b
generalZipWith f = zipper (repeat f)