I'm TAing a LISP/Prolog course at the moment, and because I didn't learn Prolog particularly well when I took the course as a student, I volunteered to write the sample solutions for the Prolog assignments. In the year or so between taking the course and TAing it, I learned Perl, and found out about regexes.

I now have an excellent mental model of Prolog's backtracking system. (Yeah, I suppose this is a glorified "Me, too!" post.) I expect this to make (re)learning Prolog much easier, and I expect (re)learning Prolog to drastically improve my regex skills.

And it looks like Perl 6 will have much better support for logical programming, which makes the exercise even more worthwhile.