title: When should I use the & to call a Perl subroutine?
body: <p>I have heard that people shouldn't be using <code>&amp;</code> to call Perl subs, i.e:</p>
  
  <pre><code>function($a,$b,...);
  # opposed to
  &amp;function($a,$b,...);
  </code></pre>
  
  <p>I know for one the argument list becomes optional, but what are some cases where it is appropriate to use the <code>&amp;</code> and the cases where you should absolutely not be using it?</p>
  
  <p>Also how does the performace increase come into play here when omitting the <code>&amp;</code>?</p>