title: pattern matching in pure functions
body: <p>I need to define a pure function that takes two arguments and returns their quotient. If the divisor is <code>0</code> then I want to return <code>0</code>.</p>
  
  <p>If I had a named function then I would do</p>
  
  <pre><code>div[_, 0]   := 0
  div[x_, y_] := x / y
  </code></pre>
  
  <p>how to do the same sort of pattern matching on arguments in a pure function <code>#1 / #2 &amp;</code>?</p>