For playing around with languages I'd actually recommend writing your own lexer and parser. It isn't hard, and writing a recursive descent parser really helps u

For playing around with languages I'd actually recommend writing your own lexer and parser. It isn't hard, and writing a recursive descent parser really helps understanding grammars and BNF. Before you have a solid grasp of how context-free grammars work, parser generators aren't much of a time saver IMO. In my experience getting a BNF grammar right is something of an art which you pick up after having written a few parsers.