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