zipo.hs

import Data.Functor.Foldable

zipo :: (Recursive f, Recursive g)
     => (Base f (g -> c) -> Base g g -> c)
     -> f -> g -> c
zipo alg xs = cata (\x -> alg x . project) xs 


zipoFix :: Functor f => (f (Fix f -> a) -> f (Fix f) -> a) -> Fix f -> Fix f -> a
zipoFix = zipo

zip :: [a] -> [b] -> [(a,b)]
zip = zipo alg
  where
    alg Nil _ = []
    alg _ Nil = []
    alg (Cons x xs) (Cons y ys) = (x,y) : xs ys