title: Java 8: Where is TriFunction (and kin) in java.util.function? Or what is the alternative?
body: <p>I see java.util.function.BiFunction, so I can do this:</p>
  
  <pre><code>BiFunction&lt;Integer, Integer, Integer&gt; f = (x, y) -&gt; { return 0; };
  </code></pre>
  
  <p>What if that is not good enough and I need TriFunction?  It doesn't exist!</p>
  
  <pre><code>TriFunction&lt;Integer, Integer, Integer, Integer&gt; f = (x, y, z) -&gt; { return 0; };
  </code></pre>
  
  <p>I guess I should add that I know I can define my own TriFunction, I'm just trying to understand the rationale behind not including it in the standard library.</p>