title: Clojure length of sequence
body: <p>I could have sworn I had <code>alength</code> working previously, but I don't quite know what I am doing wrong right now:</p>
  
  <pre><code>user=&gt; (alength '(1 2 3))
  IllegalArgumentException No matching method found: alength  clojure.lang.Reflector.invokeMatchingMethod (Reflector.java:79)
  user=&gt; (alength [1 2 3])
  IllegalArgumentException No matching method found: alength  clojure.lang.Reflector.invokeMatchingMethod (Reflector.java:79)
  user=&gt; (doc alength)
  -------------------------
  clojure.core/alength
  ([array])
    Returns the length of the Java array. Works on arrays of all
    types.
  nil
  </code></pre>
  
  <p>What should I be doing to get the length of a list/array in Clojure?</p>