title: merging two ordered lists of numbers into one with recursion
body: <p>I am new to Haskell, recursion 
  for e.g. INPUT [1,3,4,5] [6,9,8,10]
  OUTPUT = [1,3,4,5,6,8,9,10]
  My previous attempt was</p>
  
  <pre><code>&gt;let addlist [] [] = []
  
  &gt;let addlist (a:as) (b:bs) = (a+b) : addlist as bs
  &gt;let x = [1..5]
  &gt;let y = [6..10]
  &gt;addlist x y
  </code></pre>
  
  <p>But this adds the numbers in the list rather than merging them. </p>