Proposal: instance Alternative ZipList

The ZipList data type admits one legal Alternative instance instance Alternative ZipList where pure = ZipList [] ZipList xs <|> ZipList ys = ZipList (xs ++ drop (length xs) ys) The legality of this instance was first noted in http://people.cs.kuleuven.be/~tom.schrijvers/Research/papers/ppdp2015.pdf I propose adding this instance, which acts like a generalized version of the Alternative for Maybe, choosing with a left bias. Discussion Period: 2 weeks -Edward