Swi Prolog Editor only shows false, not true

Asked Oct 03 '16 at 13:30

Active Oct 03 '16 at 13:30

Viewed 496 times

Assume my knowledge base contains one fact: fact(fact1).

If I know submit a query fact(fact1).

39 ?- fact(fact1).

40 ?-

it says nothing, which is the equivalent to true. B/c if it's wrong, Prolog responds with false:

38 ?- fact(foobar).
false.

So how can I change it so I get a true. ?

asked Oct 03 '16 at 13:30

InDaPond

1

Try `fact(X).` first! – false Oct 03 '16 at 13:41
Yeah then I get all possible unifications, I do not want that. I just want to get a true. like the false. statement – InDaPond Oct 03 '16 at 13:50
with `a(a).` in my program, and querying `a(a).`, I get `true.`. What version do you use? – Fatalize Oct 03 '16 at 13:57
SWI-Prolog-Editor 4.26, 26.04.2015 SynEdit 2.05 – InDaPond Oct 03 '16 at 13:59
1

@InDaPond: That you do not get a `true` for your first query is what struck me. – false Oct 03 '16 at 14:04
Yes, this is what my question is about. The nothing there is the equivalent to true, but as you can see for yourself, it is very confusing to just not get a response at all. – InDaPond Oct 03 '16 at 14:44

0 Answers0