Rewrite Following Haskell code mystery using foldr

A programmer writes the following code but fails to provide types: data SF a = SS a IFF deriving (Show, Eq) myhead [= FF myhead (a:as) = SS a mytail [] = [] mytail (:xs) = xs myzip [] _ = [] myzip - [] = [] myzip (a:as) (b:bs) (a,b): (myzip as bs) mystery xs myhead [x (x,y)