:: Ord a => [a] -> [a] -package:focus -package:base-prelude -package:safe -package:incipit-base -package:extra -package:ghc -package:amazonka-core is:exact -package:vector-algorithms -package:errors -package:Cabal 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.