title: Group by with tuples in F#
body: <p>Suppose I have a list of  tupples like these : </p>
  
  <pre><code>[("A",12); ("A",10); ("B",1);  ("C",2); ("C",1)]
  </code></pre>
  
  <p>And I would like to do some kind of <code>groupby</code> how do I handle that?</p>
  
  <p>In pseudocode-SQL it should look something like this : </p>
  
  <pre><code>SELECT fst(tpl), sum(lst(tpl)) FROM [TupplesInList] GROUP BY fst(tpl)
  </code></pre>
  
  <p>yielding </p>
  
  <pre><code> [("A",22); ("B",1); ("C",3)]
  </code></pre>
  
  <p>I could make a  Dictionary and add the ints if the key exist, but I can hardly believe that would be the best solution in a language as expressive as F#.</p>