Returns a Parser that consumes exactly the sequence of characters in string, and fails if the input does not match or is exhausted before the full string is consumed.
Returns a Parser that consumes zero or more characters satisfying predicate, collecting them into a String. Always succeeds; returns an empty string when predicate is false for the first character or the input is exhausted.
Returns a Parser that consumes one or more characters satisfying predicate, collecting them into a String. Fails when predicate is false for the first character or the input is exhausted.