Prolog Clear List of negative elements without using cuts

Question

How do I write a procedure in Prolog that clears a list of integers of its negative elements and returns the result in a new list? Without using cuts but can use negation.

Answer 1

Using recursion for the last case,

I'd write :

filter([],[]).

filter([H|T],S) :-
  H<0,
  filter(T,S).

filter([H|T], L) :- 
 H>=0, 
 filter(T, S),
 append([H],S,L).