title: What is the first of the two type parameters of the function passed to a `collect` method in Scala?
body: <p>Why does the <a href="http://www.scala-lang.org/api/2.10.4/#scala.collection.immutable.List" rel="nofollow">method</a></p>
  
  <pre><code>def collect[B](pf: PartialFunction[A, B]): List[B]
  </code></pre>
  
  <p>declared with the method only being dependent on the type <code>B</code> (<code>collect[B]</code>)? </p>
  
  <p>The signature shows this method depends on both <code>A</code> and <code>B</code>.</p>