Quote from the link: "The most confusing thing about Prolog is that, whatever algorithm you implement with it must be on top of the built-in ones, namely depth-

Quote from the link: "The most confusing thing about Prolog is that, whatever algorithm you implement with it must be on top of the built-in ones, namely depth-first search, and unification (and only using recursion rather than iteration). " When I discovered that during my studies I decided that Prolog is not for me. First it looks neat for toy problems and then you're fighting the solver until you give up.