Prolog count the number of times a predicate is true

Question

I want to count the number of times a custom predicate is true. For example, I have the following code:

is_man(john).
is_man(alex).
?:-is_man(X).
         


        

Answer 1

count(P,Count) :-
        findall(1,P,L),
        length(L,Count).