Parslet is a small Ruby library for constructing parsers in the PEG (Parsing Expression Grammar) fashion. Parslet makes developing complex parsers easy. It does so by - providing the best error reporting possible - not generating reams of code for you to debug Parslet takes the long way around to make your job easier. It allows for incremental language construction. Often, you start out small, implementing the atoms of your language first; parslet takes pride in making this possible. WWW: http://kschiess.github.io/parslet/