:: Ord a => [a] -> [a] -package:list-t -package:errors -package:safe is:exact -package:extra -package:Cabal -package:incipit-base -package:lifted-base -package:hxt -package:vector -package:integration -package:mono-traversable package:parsers
Take a parser that may consume input, and on failure, go back to where
we started and fail as if we didn't consume input.