I just uploaded AI::Prolog 0.61. Mainly this was to fix my boo-boo of automatically leaving trace on in the Prolog shell, but I also returned to a more reasonable version numbering scheme and, just to ensure that this was not a total waste, I reimplemented fail to be an internal predicate, thus making it slightly faster, and I added var(X), a goal which succeeds if X is an unbound variable.
