title: Simple function literal produces missing parameter type
body: <p>With Scala 2.12, I can do this:</p>
  
  <pre><code>Try("3").fold(_.toString, _.toString)
  </code></pre>
  
  <p>but I can't this:</p>
  
  <pre><code>Try("3").fold(_.toString, _)
  </code></pre>
  
  <p>This is the error I receive:</p>
  
  <pre><code>missing parameter type for expanded function
  </code></pre>
  
  <p>Why a complicated expression does work and a simple one doesn't?</p>
  
  <p>My workaround:</p>
  
  <pre><code>Try("3").fold(_.toString, x =&gt; x)
  </code></pre>