title: Subtracting or adding lists of lists in prolog?
body: <p>I am fairly new to prolog and am trying to mess around with lists of lists. I am curious on how to add two lists of lists or subtract them resulting in one list of list. If I have two lists of lists lets say, </p>
  
  <pre><code>SomeList = [[1,2,3,4],[5,6,7,8]]  
  SomeList2 = [[1,2,3,4],[5,6,7,8]]
  </code></pre>
  
  <p>How could I add or subtract <code>SomeList</code> and <code>SomeList2</code> to create a list of lists? Resulting in a sum of say</p>
  
  <pre><code>sumList([[2,4,6,8],[10,12,14,16]]) 
  </code></pre>
  
  <p>or vice-versa for subtraction? Any help would be appreciated not looking for code but for insight !</p>