title: Erlang: Get the first element of each tuple in a list
body: <p>I can get the first element of every tuple if I create the list at the same time, for example</p>
  
  <pre><code>[element(2,X) || X &lt;- [{1,2},{3,4}]].
  [2,4]
  </code></pre>
  
  <p>This works as it should.
  I want to be able to create the list before I try to do anything with it</p>
  
  <p><strong>Ex: Create the list</strong></p>
  
  <pre><code>X = [{1,2,3},{3,4,5}]. 
  [{1,2,3},{3,4,5}]
  </code></pre>
  
  <p><strong>Then get the first element of each tuple</strong></p>
  
  <pre><code>element(1,X).
  </code></pre>
  
  <p>But I get the error</p>
  
  <pre><code>** exception error: bad argument
       in function  element/2
          called as element(1,[{1,2,3},{3,4,5}])
  </code></pre>
  
  <p>I want this code to give the same results that my first example gave</p>