title: Break array_walk from anonymous function
body: <p><strong>Is there a way to stop an <code>array_walk</code> from inside the anonymous function ?</strong></p>
  
  <p>Here is some sample code (that works) to show what I mean, that checks if an array has only numeric values.</p>
  
  <pre><code>$valid = true;
  array_walk($parent, function ($value) use (&amp;$valid) {
      if (!is_numeric($value)) {
          $valid = false;
      }
  });
  
  return $valid ? 'Valid' : 'Invalid';
  </code></pre>
  
  <p>If I have a big enough array, and the first entry is invalid, the rest of the (redundant) checks are still done, so I would like to stop the execution.</p>
  
  <p>Using <code>break</code> / <code>continue</code> doesn't work (error: <code>Fatal error: Cannot break/continue 1 level in ...</code>).</p>
  
  <p><strong>Note:</strong> I don't want to rewrite the code, I just want to know <strong>IF</strong> this is possible.</p>