Prolog
I've tried using Turbo Prolog about 8~7 years ago. Compared to other languages, it's good enough -- just for AI, not other purposes. It's a little bit hard to formulate the problem into Prolog structure to get it's power for the first times, specially if we used to use many other languages. We likely 'framed' to procedural algorithm. But when we found it's philosophy of design, it such a wonderful AI language.
Why?
Because:
- it based on rule and data, not how to do.
- it's logic based on comparing facts (or we can say patern), similar with the way human think.
- it have fascinating internal backtracking/cut algorithm.
- it can change it's 'logic' caused by the 'fact' (it's knowledge/data) after compiled.
I agree with kmguru that prolog should have more advanced classes to handle I/O. In the previous version i've tried, it just looks like brain without nerves of sensor. To make it usefull, we must combine it with C.
I haven't try the visual versions, yet. As a knew the newest version of Visual Prolog is version 5.x (free, ~50MB installer at CNet/ZDnet).