Looks like I haven't been paying attention to the prolog world. Since I last looked they've also gone all OO. Just heard about logtalk, which strikes me as interesting and perhaps coming back to. Description from freshmeat: Logtalk is an open source object-oriented extension to the Prolog programming language. Integrating logic programming with object-oriented and event-driven programming, it is compatible with most Prolog compilers. It supports both prototypes and classes. In addition, it supports component-based programming through category-based composition.

So not quite the prolog I originally learnt then ... :-) Or perhaps as prolog would say: no. Mind you, I've always thought that if prolog could be made useable by the average person that it would have some really interesting applications for users. After all, being declarative it does allow you to do a lot more by doing a lot less. You've got to wonder what the implications of a tutorial on event based systems in prolog where messages to objects are events have for other systems.