How to multiply all elements of two lists with each other in Prolog

Question

I am thinking how to multiply all elements of two list with each other. Then I want to put all results in List3. For example,

List1 = [1,3,5].
List         


        

Answer 1

A simple solution not requiring any Prolog extensions (but, of course, loosing the potential benefits of using CLP(FD)) would be:

product(List1, List2, Product) :-
    % save a copy of the second list
    product(List1, List2, List2, Product).

product([], _, _, []).
product([X| Xs], List2, Rest2, Product) :-
    (   Rest2 == [] ->
        product(Xs, List2, List2, Product)
    ;   Rest2 = [Y| Ys],
        Z is X * Y,
        Product = [Z| Zs],
        product([X| Xs], List2, Ys, Zs)
    ).

This solution is tail-recursive and doesn't leave spurious choice-points.