you can be unifying and verifying under Perl!
I have often wanted to write an article called AI::Prolog::DontBother
It is much easier to map human reasoning to Perl than to Prolog. Actually CLIPS is a pretty good rule/expert system, and Mercury is a great step forward past Prolog, integrating functional and logic programming.
And a good book on the subject is David H.D. Warren's "Computing with Logic: Logic Programming in Prolog" which moves through propositional, predicate and functional logic (the last of which is what prolog uses).
An implementation of the first (propositional) logic is available in AI::Proplog.
But like I said, I dont think Prolog is really any more powerful than Perl and even though object and functional and procedural mechanisms are available in Perl, logical ones are not here and not apparently needed. ref Prolog-Perl Golf Association