domains
    x = integer
    l = integer*
    
predicates
    length(l,x)
    evenlength(l)
    oddlength(l)
    
clauses
    length([],0).
    
    length([X|List],Length) :-
        length(List,Length1),
        Length = Length1 + 1.
        
    evenlength(List) :-
        length(List,Length),
        Length mod 2 = 0.
    
    oddlength(List) :-
        length(List,Length),
        Length mod 2 <> 0.
        
Output :

For evenlength :

Goal: evenlength([1,2,3,4])
Yes

Goal: evenlength([1,2,3,4,5])
No

For oddlength :

Goal: oddlength([1,2,3,4,5])
Yes

Goal: oddlength([1,2,3,4])
No