title: swipl: how to reload file
body: <p>First I load the file with <code>SWI-Prolog</code></p>
  
  <pre><code>$ swipl file.pl
  </code></pre>
  
  <p>then I modify the file and save.</p>
  
  <p>Now how do I reload the file like</p>
  
  <pre><code>?- reload
  </code></pre>
  
  <p>for this modified <code>file.pl</code>?</p>