prologprolog-toplevel

Get multiple solutions in SWI-Prolog using toplevel

I'm beginner in SWI-Prolog (but have some experience in Borland Prolog), and I've faced with a strange behavior for the following test code:

test(10).
test(1).

It is expected for query ?-test(A) to get 2 solutions, something like A = 10; A = 1. However, only A = 10 is produced. I don't use the cut here. Maybe backtracking is off by default in SWI-Prolog?

Thanks in advance

Solution

  • Sorry, the answer is very simple (see SWI-Prolog doc):

    The user can type the semi-colon (;) or spacebar, if (s)he wants another solution. Use the return key if you do not want to see the more answers. Prolog completes the output with a full stop (.) if the user uses the return key or Prolog knows there are no more answers. If Prolog cannot find (more) answers, it writes false.