:: Ord a => [a] -> [a] -package:list-t -is:exact -package:safe -package:base-prelude -package:ghc -is:exact -package:Cabal -package:Cabal-syntax -package:amazonka-core -package:lifted-base -package:base package:parsers -is:exact
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.