title: Common Lisp: getting all keys of a given hash table as a list
body: <p>I wonder if there is a less verbose way than using a loop. Anyway this works for me in CLISP:</p>
  
  <pre><code>(loop for key being the hash-keys of *my-hash* collect key)
  </code></pre>
  
  <p>I've seen others using <code>maphash</code>, but that involves accumulating each key into a list. Apart from that being more involved than using loop, it also introduces a side-effect, which I try to avoid whenever I can - I prefer functional programming as much as possible :)</p>
  
  <p>Is there anything predefined like this for this common task, even though implementation-specific?</p>
  
  <pre><code>(defun hash-keys (hash-table)
    (loop for key being the hash-keys of hash-table collect key))
  </code></pre>