:: Ord a => [a] -> [a] -package:html-entities -package:statistics -package:extra -package:Cabal-syntax -package:integration -package:base-prelude -package:imports -package:Cabal -package:errors -package:generic-deriving -package:containers -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.