This may be of some interest to you: http://lfw.org/python/rxb.py -- it hasn't caught on since 1996 though.

I've seen some swear to OMeta which is the parser used in the VPRI "simple OS" product, powerful enough to implement a bare-bones TCP/IP implementation as essentially drawings; http://www.moserware.com/2008/04/towards-moores-law-software...