title: Scala maps -> operator
body: <p>What does the symbol <code>-&gt;</code> mean in the context of a <code>Map</code> in Scala?</p>
  
  <p>Scala’s <code>Predef</code> class offers an implicit conversion that lets one write 
  <code>key -&gt; value</code> as an alternate syntax for the pair <code>(key, value)</code>. 
  I read it in ScalaByExample but fail to see how this works for Maps.</p>