title: Haskell - Defining result as a list and returning null
body: <pre><code>listX n = xs
  if sum[x | x &lt;- [2, 4..n-1], y &lt;- [1..n-1], y `rem` x == 0] == y
      then insert y xs
      else return ()
  </code></pre>
  
  <p>Alright, first time trying to work with Haskell, and only having novice Java knowledge has led to some problems. 
  What I was trying to do, was to define the result of the function listX n as a list called xs.
  My idea was that the program would grab every number of from 1 to n, and check if it was equal to the sum of its positive divisors.
  Clearly, I have failed horribly and need help, pointers to concepts I haven't understood is extremely appreciated.</p>