title: Modifying a property list
body: <p>I have a <a href="http://clhs.lisp.se/Body/26_glo_p.htm#property_list" rel="nofollow">property list</a>:</p>
  
  <pre><code>(setf *star* '(:points 5))
  </code></pre>
  
  <p>I'd like to modify this plist. Sometimes the better choice is to do mutation, and sometimes the better choice is to use an immutable update.</p>
  
  <p>How to modify the plist using <strong>mutation</strong>?</p>
  
  <pre><code>(mutate *star* :points 6)
  *star* ; '(:points 6)
  </code></pre>
  
  <p>And how to modify the plist using an <strong>immutable update</strong>?</p>
  
  <pre><code>(update *star* :points 6) ; '(:points 6)
  *star*                    ; '(:points 5)
  </code></pre>