title: Single call-by-name constructor arg not required?
body: <p>Why does line #2 below compile? It's (seemingly) not giving the required constructor arg.</p>
  
  <pre><code>class F(x: =&gt; Unit) {}
  new F                     // Compiles (strange)
  def f(x: =&gt;Unit) = ()
  f                         // Does not compile (good)
  </code></pre>
  
  <p>Is it permitted sugar just for this special case? Can you point to docs on the subject? I'm using Scala 2.9.0.</p>