A paper by ClausBraband and MichaelSchwartzbach of the University of Aarhus (Denmark) on the macro preprocessor used in <BigWig>. Compares and contrasts it with many other macro preprocessors, including those of CeePlusPlus, SchemeLanguage (DefineSyntax), DylanLanguage, and a few others. Interesting read.
Available online at http://www.brics.dk/bigwig/publications/macro.pdf
Supposedly, a similar system is in NeedleLanguage.