in reply to Rules based Perl

If you don't mind a work around: there's an excellent rule engine in Java called Jess. You could access it from Perl using the Java module. The latter allows to create Java objects and treat them as if they were Perl.

A book on Jess has recently been reviewed on slashdot as well as on Jess is related to and mostly backward compatible with the CLIPS engine mentioned by sauoq.

Hope this helps, -gjb-