[tocomment]

I think it just means writing a programming language but a little one. So use pyparsing as your parser. The May 2008 Python magazine has a good article on making an interpreter/compiler for brainf*ck using PyParsing.

[wilkes]

I've really enjoyed using PyParsing. O'Reilly has a ShortCut book on it that is worthwhile. http://oreilly.com/catalog/9780596514235/