I had no idea there was such thing as an improper suffix. Here's a quibble-free parser which returns a tail which is neither a "proper suffix nor a suffix".

I had no idea there was such thing as an improper suffix. Here's a quibble-free parser which returns a tail which is neither a "proper suffix nor a suffix". earlyTerminate c = Parser $ \s -> case s of [] -> Right (s, ()) (x:xs) | x == c -> Right ("", ()) | otherwise -> Left "Not a terminator" > although considerable care would be needed with backtracking No shit. Show your example.