title: foldr and foldl further explanations and examples
body: <p>I've looked at <a href="http://www.haskell.org/haskellwiki/Foldr_Foldl_Foldl%27" rel="noreferrer">different folds</a> and <a href="http://haskell.org/haskellwiki/Fold" rel="noreferrer">folding in general</a> as well as a few others and they explain it fairly well.</p>
  
  <p>I'm still having trouble on how a lambda would work in this case. </p>
  
  <pre><code>foldr (\y ys -&gt; ys ++ [y]) [] [1,2,3]
  </code></pre>
  
  <p>Could someone go through that step-by-step and try to explain that to me?</p>
  
  <p>And also how would <code>foldl</code> work?</p>