title: Convert various length of List to Tuple in Haskell
body: <p>I want convert list [[1,2,3],[2,3]] to tuple [(1,2,3),(2,3)]</p>
  
  <p>my function: </p>
  
  <pre><code>thr [a,b,c] = (a,b,c)
  tupel [] = []
  tupel (x:xs) = if length x==3 then thr x:(tupel xs) else (tupel xs)
  </code></pre>
  
  <p>this work with three Elements.</p>
  
  <pre><code>thr [a,b,c] = (a,b,c)
  two [a,b]   = (a,b)
  tupel [] = []
  tupel (x:xs) = if length x==3 then thr x:(tupel xs) else two x:(tupel xs)
  </code></pre>
  
  <p>why don´t work this? </p>
  
  <p>Error: Type error in application
  <strong>* Expression     : two x : tupel2 xs
  <em></strong> Term           : two x
  <strong></em> Type           : (a,a)
  *</strong> Does not match : (a,a,a)</p>