title: Scheme: Return a list of positive values
body: <p>So my input is some list l, and the goal of the function is to take all of the positives and make a new list with just these positive values. This is what I've currently got:</p>
  
  <pre><code>(define (positives l)
    (define (poscheck l)
      (cond ((negative? (car l)) '())
            ((null? l) '())
            (else (poscheck (cdr l)))))
  (list (poscheck l)))
  </code></pre>
  
  <p>For some reason, it keeps telling me that it's given an empty list when checking (car l). I'm not exactly sure what it's picking up on for the error. Any help with fixing this code would be appreciated.</p>