title: "=>" operator in Scala
body: <p>I'm new to Scala and has searched over here but didn't find the answer. I'm wondering what is this operator mean "x: => Boolean" in argument context of the function.</p>
  
  <pre><code>package scala
  abstract class Boolean {
  def &amp;&amp; (x: =&gt; Boolean): Boolean 
  def || (x: =&gt; Boolean): Boolean
  }
  </code></pre>
  
  <p>I know that <code>def example(x: Int =&gt; Boolean): Boolean</code> would mean anonymous function that takes Int and return Boolean. However, what it means if argument omitted?</p>