title: Using Search operator to find out only if there is a match
body: <p>When using the operator ⎕S in Dyalog APL I'm only interested in if there is a match or not, so the expression</p>
  
  <pre><code>('foo' ⎕S F) 'foo' 'bar' 'foofoo'
  </code></pre>
  
  <p>should evaluate to</p>
  
  <pre><code>.→----.
  |1 0 1|
  '~----'
  </code></pre>
  
  <p>What function (or string) <em>F</em> will achieve this?</p>
  
  <p>Edit: The example is just to illustrate the point. In practice the regular expression can be much more complicated.</p>