Superfluous (is)/2?

[triska]

With p/2 defined as:

p(A, B) :-
        B is A + 3.

I get:

?- wam_instructions(p/2, Is),
   maplist(portray_clause, Is).
get_variable(x(3),1).
put_value(x(2),1).
add(x(3),3,1).
execute(is,2).

Can the execute(is,2) be removed? It seems that "adding 3", i.e., add(...) is everything that's needed here, if that primitive can be made to unify the result directly with B.

[mthom]

The add puts the sum into an intermediary value vector that's read by is/2.