title: hashtable keys that are strings not recognized
body: <p>Scheme's <code>eqv-hashtable</code> data structure doesn't seem to recognize keys that are strings. In the following code, I am creating a <code>eqv-hashtable</code>and creating a new datum:</p>
  
  <pre><code>(define state-hash (make-eqv-hashtable))
  (hashtable-set! state-hash "S" (State "S" #f '() '()))
  </code></pre>
  
  <p>However, when I try to check to see if my data was stored in the hashtable, I encounter the following:</p>
  
  <pre><code>(hashtable-contains? state-hash "S")  ; --&gt; #f
  </code></pre>
  
  <p>Though the <code>hashtable-contains?</code> procedure shows that key <code>"S"</code> is currently not in the hashtable, the following suggests otherwise:</p>
  
  <pre><code>(hashtable-keys state-hash)   ; --&gt; #("S")
  </code></pre>
  
  <p>If I use something other than a string for the key, for example a symbol (e.g. <code>'S</code>), I don't have any problems. Any ideas why it wouldn't like a string as a key?</p>