That was the perfect example for me; thank you so much. I now understand what constraints are and how useful they can be. My mind is now in a similar state to when I first learned of functional programming after about seven years of imperative programming. Wow. :satisfied grin:

Tomorrow I present my project to the chair of the Computer Science Department for final approval. Methinks that adding constraints to the language will make an excellent project for the summer or fall semester.

On another note, does the syntax of the language bother anyone? Specifically the fact that a predicate can return a list? I'm afraid that some people -- especially those with a strong Prolog background -- may find that notion uneasy.

Thanks again!

-Steven

Note that your language contains both predicates and functions. A clever idea would be to cleanly distinguish them.

You can define a Boolean type for predicates, and a typecast from empty and non-empty function returns to boolean. The typecast may be implicit (maybe in the :- operator?) or explicit.

I was thinking about that as I lay in bed this morning. My initial idea was to allow predicates to return lists, but my teacher was having trouble with that. So I started thinking of implementing predicates as a boolean function [easily definable in Haskell] with the ability to unify with other predicates, which actually seems to be easier from an implementation standpoint.

Boy, aren't the things I think about in bed oh-so interesting? :rolleyes:

-Steven