Dnia 8 Sierpnia 2015, 13:59, So, Donald Winiecki napisał: > I have a question about exercise 2.2 in LPN!. > > In particular, it appears to be the case that GProlog returns different > results than does SWI-Prolog on question 5 in exercise 2.2.
The heart of the problem is the clause: magic(X) :- wizard(X). In the program code predicate wizard is referenced but defined nowhere. > I understand SWI-Prolog's results, but don't understand why GProlog > stops when it hits the rule "magic(X):- wizard(X)." Any pointers > are terrifically appreciated! I have the opposite problem! I understand GNU Prolog's approach but fail to grasp why SWI does not signal missing definitions by default. :-p Anyway, how the solver behaves when it hits nonexistent procedure is configurable. Use set_prolog_flag(unknown, X) where X can be 'error', 'fail' or 'warning' to change it. -- Michał _______________________________________________ Users-prolog mailing list Users-prolog@gnu.org https://lists.gnu.org/mailman/listinfo/users-prolog
