:: Ord a => [a] -> [a] -package:html-entities -package:base-prelude -package:lens -package:base -package:extra -package:mono-traversable -package:lifted-base -package:Cabal-syntax is:exact -package:errors -package:witherable -package:vector 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.