title: Passing lambda instead of interface
body: <p>I have created an interface:</p>
  <pre><code>interface ProgressListener {
      fun transferred(bytesUploaded: Long)
  }
  </code></pre>
  <p>but can use it only as an anonymous class, not lambda</p>
  <pre><code>dataManager.createAndSubmitSendIt(title, message,
  object : ProgressListener {
      override fun transferred(bytesUploaded: Long) {
          System.out.println(bytesUploaded.toString())
      }
  })
  </code></pre>
  <p>I think it should be a possibility to replace it by lambda:</p>
  <pre><code>dataManager.createAndSubmitSendIt(title, message, {System.out.println(it.toString())})
  </code></pre>
  <p>But I am getting error: <code>Type mismatch; required - ProgressListener, found - () -&gt; Unit?</code></p>
  <p>What am I doing wrong?</p>