Parser combinator library for Ruby inspired by Haskell's Parsec

This is a library used to define parsers by declaratively describing a syntax using what's commonly referred to as combinators. Parser combinators are functions that take parsers as inputs and/or return parsers as outputs, i.e. they combine parsers into new parsers.As an example, between is a combinator with 3 parameters: a parser for what's to the left, one for what's to the right, and lastly one for what's in-between them, and it returns a parser that, after parsing, returns the result of the in-between parser:.