Inferring parameter type for a lambda (again!) : <p>I am wondering why does this not work (missing parameter type)?  </p>

<pre><code> Seq(1,2,3).toSet.map(_ + 1)
</code></pre>

<p>but this does: </p>

<pre><code> val foo = Seq(1,2,3).toSet
 foo.map(_ + 1)
</code></pre>

<p>as well as this: (3)</p>

<pre><code>  Seq(1,2,3).toSet[Int].map(_ + 1)
</code></pre>

<p>or this: </p>

<pre><code>  Seq(1,2,3).toList.map(_ + 1)
</code></pre>

<p>What is special about <code>toSet</code> that makes it loose the type in the first case, but not in the second?</p>
