title: How do I iterate through a directory in Common Lisp?
body: <p>I'm using OpenMCL on Darwin, and I'd like to do something like:</p>
  
  <pre><code>(loop for f in (directory "somedir")
    collect (some-per-file-processing f))
  </code></pre>
  
  <p>But I can't get <code>directory</code> to return anything other than <code>NIL</code>, and I can't seem to find any good explanation online (other than "its different for each system").</p>
  
  <p>Any pointers?</p>