Mini-languages in Python

Python is such a wonderfully simple and extensible language that I'd suggest merely creating a comprehensive python module, and coding against that.

I see that while I typed up the above, PLY has already been mentioned.

Pyparsing is handy for writing "little languages". I gave a presentation at PyCon'06 on writing a simple adventure game engine, in which the language being parsed and interpreted was the game command set ("inventory", "take sword", "drop book", etc.). (Source code here.)

You can also find links to other pyparsing articles at the pyparsing wiki.

I would recommend funcparserlib. It was written especially for parsing little languages and DSLs and it is faster and smaller than pyparsing (see stats on its homepage). Minimalists and functional programmers should like funcparserlib.

Edit: By the way, I'm the author of this library, so my opinion may be biased.

I have limited but positive experience with PLY (Python Lex-Yacc). It combines Lex and Yacc functionality in a single Python class. You may want to check it out.

Fellow Stackoverflow'er Ned Batchelder has a nice overview of available tools on his website. There's also an overview on the Python website itself.