title: foldl . foldr function composition - Haskell
body: <p>So, I'm really frying my brain trying do understand the foldl.foldr composition.
  Here is a example:</p>
  
  <pre><code>(foldl.foldr) (+) 1 [[1,2,3],[4,5,6]]
  </code></pre>
  
  <p>The result is 22, but what's really happening here?</p>
  
  <p>To me it looks like this is what is happening: <code>foldl (+) 1 [6,15]</code>.
  My doubt is related to the <code>foldr</code> part. Shouldn't it add the 1 to all the sub-lists? Like this: <code>foldr (+) 1 [1,2,3]</code>.
  In my head the 1 is added just one time, is it right? (probably not, but I want to know how/why!).</p>
  
  <p>I'm very confused (and perhaps making all the confusion, haha).
  Thank you!</p>