Ah CLIPS! There are a few moments in my life as a young programmer that I remember as mind-expanding. CLIPS was one of those moments (along with arrays, files

Ah CLIPS! There are a few moments in my life as a young programmer that I remember as mind-expanding. CLIPS was one of those moments (along with arrays, files and recursion). It's forward-chaining (not backward, as Prolog is) so you can see the database of facts build up step by step. A nice bridging point between procedural and declarative programming. And a foot in the door for parens-based syntax (it looks a bit like LISP) without the s-expression model.