How can i filter a list by 2 conditions?

Question

I'm new to prolog and i can't find a solution to filter list by 2 conditions, save result into 2 variables and then evaluate answer base on them.
In my case, if list contains more numbers that greater then 0, then numbers lesser then 0.

For example i get a list with elements:

checklist([-2, 3.3, 12, -10.1, 14, -11, 123]) # true
checklist([-2.1, -3, -4, 14, 16.7])           # false
checklist([11.5, 2.5, -34.1, -1])             # false

I'd write something like this in python:

bigger_count = 0
lesser_count = 0
for num in list:
    if num > 0:
        bigger_count += 1
    elif num < 0:
        lesser_count += 1
print(bigger_count > lesser_count)

Especially i doesn't understand how to work with 2 variables at one time.

Answer 1

Another possible solution is:

check(List) :-
    check(List, Balance),
    Balance > 0.

check([], 0).
check([X|Xs], B) :-
    check(Xs, B0),
    (   X > 0 -> B is B0 + 1
    ;   X < 0 -> B is B0 - 1
    ;            B is B0 ).

Examples:

?- check([-2, 3.3, 12, -10.1, 14, -11, 123]).
true.

?- check([-2.1, -3, -4, 14, 16.7]).
false.

?- check([11.5, 2.5, -34.1, -1]).
false.

?- check([1,-1]).
false.