AI::Prolog 0.7 has been uploaded to the CPAN. A quick summary of the (many) enhancements:
X is N + 1. % is(X, plus(N, 1)).
Incidentally, if you've been using the shell, this now means that you can consult files directly in the shell rather than doing one file at a time one the command line.
Oh, and over 130 new tests.