Hi Haskellers! I'm currently trying to write an assembler for Knuths MMIXAL language. Currently, I'm writing the parser using attoparsec, and have one question: In MMIXAL, a string literal starts with a ", followed by an arbitrary amount of arbitrary characters excluding the newline character and finished with another ". For example: "Hello, World!" is a string, "ſ" is a string too, but "\n" (\n is a newline) isn't. Here's the parser, which parses a s tring and other kinds of constants: parseConstant = Reference <$> try parseLocLabel <|> PlainNum <$> decimal <|> char '#' *> fmap PlainNum hexadecimal <|> char '\'' *> (CharLit <$> notChar '\n') <* char '\'' <|> try $ (char '"' *> (StringLit . B.pack <$> manyTill (notChar '\n') (char '"'))) "constant" The problem is, that attoparsec just silently fails on this kind of strings and tries other parsers afterwards, which leads to strange results. Is there a way to force the whole parser to fail, even if there's an alternative parser afterwards? I hope, you understand my question. Yours, Robert Clausecker