title: Using list comprehension with two variables in haskell
body: <p>does someone know how I can do a list comprehension with two variables in haskell? </p>
  
  <p>ex. </p>
  
  <pre><code>[ x * y  | x &lt;- [1..10]  y &lt;- [1..10]]
  </code></pre>
  
  <p>it should result in </p>
  
  <pre><code>[1,4,9,16,25,36,49,64,81,100]
  </code></pre>
  
  <p>but it actually yields in ghci</p>
  
  <pre><code>&lt;interactive&gt;:13:23-24: error:
      parse error on input ‘&lt;-’
      Perhaps this statement should be within a 'do' block?
  </code></pre>