title: How can spark-shell work without installing Scala beforehand?
body: <p>I have downloaded Spark 1.2.0 (pre-built for Hadoop 2.4). In its quick start doc, it says:</p>
  
  <blockquote>
    <p>It is available in either Scala or Python.</p>
  </blockquote>
  
  <p>What confuses me is that my computer doesn't have Scala installed separately before (OS X 10.10), but when I type <code>spark-shell</code> it works well, and the output shows: </p>
  
  <pre><code>Using Scala version 2.10.4 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_25)
  </code></pre>
  
  <p>as depicted in the screenshot:</p>
  
  <p><img src="https://i.stack.imgur.com/vhEmo.png" alt="enter image description here"></p>
  
  <p>I didn't install any Scala distribution before.</p>
  
  <p>How can spark-shell run without Scala?</p>