This is old code, but it has sparked a great discussion here. In the 1980s I spent months writing a prototype planning system in Common Lisp (which is a primar

This is old code, but it has sparked a great discussion here. In the 1980s I spent months writing a prototype planning system in Common Lisp (which is a primary language for me, and I wrote a CL book for Springer-Verlag back then). Even though I was a Prolog novice, I was able to rewrite my entire prototype in Prolog in one week. Admittedly this was because the second implementation of something is always easier, but also because Prolog was such a good fit to this particular problem. I remember reading The Fifth Generation Computer about Japan’s AI efforts - enjoyed the book but it didn’t really click for me, mostly because I had a Lisp Machine and considered that the `one true path` for AI development at the time.