title: What does Post.all.map(&:id) mean?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1217088/what-does-mapname-mean-in-ruby">What does map(&amp;:name) mean in Ruby?</a>  </p>
  </blockquote>
  
  
  
  <pre><code>Post.all.map(&amp;:id) 
  </code></pre>
  
  <p>will return </p>
  
  <pre><code> =&gt; [1, 2, 3, 4, 5, 6, 7, ................] 
  </code></pre>
  
  <p>What does <code>map(&amp;:id)</code> mean? Especially the <code>&amp;</code>.</p>