I'm trying to run the program but I get an error:

Sandbox restriction! Could not derive which predicate may be called from call(C) expression1(A,B) combined_expression(A,B,C) solve

expression1(C, J) :-
(C, \+J);
(\+C, J).

expression2(J, D) :-
    (J, \+D);
    (\+J, D).


expression3(D, C, J) :-
    (
        D,
        \+ C,
        \+ J
    );
    (
        \+ D,
        (C ; J)
    ).

values([true, false]).

combined_expression(C, J, D) :-
    write('C = '), write(C), write(', '),
    write('J = '), write(J), write(', '),
    write('D = '), writeln(D),
    expression1(C, J),
    expression2(J, D),
    expression3(C, J, D).    

solve:-
    values(Values),
    member(A, Values),
    member(B, Values),
    member(C, Values),
    combined_expression(A, B, C).

How can this be fixed?

I'm trying to run the program but I get an error:

Sandbox restriction! Could not derive which predicate may be called from call(C) expression1(A,B) combined_expression(A,B,C) solve

expression1(C, J) :-
(C, \+J);
(\+C, J).

expression2(J, D) :-
    (J, \+D);
    (\+J, D).


expression3(D, C, J) :-
    (
        D,
        \+ C,
        \+ J
    );
    (
        \+ D,
        (C ; J)
    ).

values([true, false]).

combined_expression(C, J, D) :-
    write('C = '), write(C), write(', '),
    write('J = '), write(J), write(', '),
    write('D = '), writeln(D),
    expression1(C, J),
    expression2(J, D),
    expression3(C, J, D).    

solve:-
    values(Values),
    member(A, Values),
    member(B, Values),
    member(C, Values),
    combined_expression(A, B, C).

How can this be fixed?

• prolog
• swi-prolog-for-sharing

1 Answer 1

You haven't said, but that error message looks like it is from SWISH - a restricted shared web environment. As a security protection to stop people attacking it, SWISH will only run code that it can make sure is not an attack. By putting a term into C and executing it with (C, \+J) SWISH cannot be sure the code is safe for it, and will not run it.

You can download SWI Prolog and install it locally, and run any code you want.