title: How can I generate a random array containing 0-9 and a-z, in APL
body: <p><code>?5 5⍴CHARS</code> where <code>CHARS</code> is a variable containing 0-z.</p>
  
  <p>The roll operator won't accept <code>CHARS</code> since it contains elements that are not non-negative integers, namely the letters a-z.</p>