Get multiple solutions in SWI-Prolog using toplevel

Question

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

Lithic

when A=10 returned pres ; to get another solutions and so on... – Sava

Coder, many thanks for reply, and sorry for stupid question. I didn't expect that it is necessary to press Spacebar or semicolon after each solution, and I pressed Return. – Lithic

Answer 1

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.

Lithic

The manual is a great source of information for how the basic aspects of SWI Prolog works. – Alejandro

When should you "type the semi-colon"? After entering a query like ?-pred(X). I must press enter to get the solution, which also brings me to a new line where I can only enter after ?- as if another query. – Preexist

user289661, type semicolon after getting solution, f you want to get other solutions. If you don't need more solutions, press enter. – Lithic

Answer 2

bagof/3 is probably what you're looking for.

?- bagof(X, test(X), Xs).

where Xs is a list of all matching results.
Know that anonymous variables don't work how you might expect with bagof. In the following example:

test(1,odd).
test(2,even).
test(3,odd).
test(4,even).

bagof(X, test(X,_), Xs) will only give values of X where the second term is uniform; in this case only the even numbers. If you want to return all matching value you need to do something like

?- bagof(X, A^test(X,A), Xs).

Luggage

Jordan C.M., thanks for reply. There is also findall, thanks. I sought a way to see multiple solution from console, but your info is useful, thansk again. – Lithic