I'm pleased to say that Parrotlog is now at a point where it can actually do stuff. It can call predicates and backtrack (more on that in a moment). Unification probably works as well.

Now, backtracking is tricky to get right. Currently Parrotlog has a problem with cuts. A cut is supposed to remove all choice points encountered after the currently executing predicate was invoked. Parrotlog's cut prunes all choice points since the invocation of the last predicate that matched successfully. Close, but no cigar.

Graham's CL implementation (that Parrotlog owes quite a bit to) solv…