Prolog is considered difficult by students. Usually, by the time they learn Prolog, which is most likely to happen in preparation for a course in Artificial Intelligence (AI) or Expert Systems, they will have studied imperative programming and/or the object oriented paradigm. Unfortunately, this prior experience is not always conducive to learning Prolog. Even though there is a good provision of traditional Prolog textbooks (for example [2]), students still find it hard to write solutions in Prolog to problems of any notable complexity. In my experience this holds also (and in particular) for problems for which Prolog should be the natural choice
