title: all elements of a List * List
body: <p>I'm trying to do a list of tuples with 2 lists of like this: </p>
  
  <pre><code>["a", "b", "c"] ["a", "b", "c"]
  </code></pre>
  
  <p>to this:</p>
  
  <pre><code>[("a", "a"), ("a", "b"),("a", "c")], [("b", "a"), ("b", "b"), ("b", "c"), ("c", "a"), ("c", "b"), ("a", "c")]
  </code></pre>
  
  <p>so I'm trying this, but I don't know how can I make that work:</p>
  
  <pre><code>f [] [] = [[]]
  f (x:xs) y =
           zip (repeat x) y: f xs y
  </code></pre>