This tool is written in the Scheme programming language. It generates parsers based on tagged regular expressions. It is well suited to parse irregular languages containing complex lexem rules. For example, it can be used to decode WMO bulletins.
The package is available as a gzip tar file (version 1.1b): RegReg.tar.gz
RegReg HTML documentation
RegReg PDF documentation
A presentation made in October 29th, 2002, at the International Lisp Conference, San Francisco, covering Metcast fastCGI and RegReg applied to meteorological decoders, is available here: in PostScript, in PDF.
A paper, titled RegReg: a Lightweight Generator of Robust Parsers for Irregular Languages appeared in the proceedings of WCRE 2003, Novembre 2003, shows an application of RegReg in reverse engineering.
The slides, in PDF, of a "demo" presentation, for October 21th, 2003, is available here.