Prolog count list elements higher than n

Question

I\'m kinda new to Prolog so I have a few problems with a certain task. The task is to write a tail recursive predicate count_elems(List,N,Count) condition

Answer 1

Seems you didn't consult your source file.

When you will fix this (you could save these rules in a file count_elems.pl, then issue a ?- consult(count_elems).), you'll face the actual problem that Count it's a singleton in first rule, indicating that you must pass the counter down to actual tail recursive clauses, and unify it with the accumulator (the Count that gets updated to Count1) when the list' visit is done.

You'll end with 3 count_elems/4 clauses. Don't forget the base case:

count_elems([],_,C,C).