title: What does "outer =>" really mean?
body: <p>Is there any documentation on the "outer =>" feature? It looks like a self type annotation with an infered type. However I have the feeling that I am wrong.</p>
  
  <p>If it would be the case, is it only a different way to express access to <code>super</code>?</p>
  
  <pre><code>trait A extends (B =&gt; C) {
    outer =&gt;
    def apply(x: B): C = outer(x)
  }
  </code></pre>