Call different predicate if variable is not instantiated

Question

Having this snippet

foo :- getVar(X).

How can I do a really simple thing such as: "if the variable X comes out of getVar instatiated, call bar/1 else call baz/1

Thanks!

Answer 1

You can use an if-then-else control construct and the nonvar/1 standard built-in predicate. For example:

foo :-
    get_var(X),
    (   nonvar(X) ->
        bar(X)
    ;   baz(X)
    ).