patch applied (ghc): Fix DoCon: Another try at getting extractResults right

[Simon Peyton Jones]

Fri Oct 12 09:23:25 PDT 2007  simonpj at microsoft.com
  * Fix DoCon: Another try at getting extractResults right
  
  For some reason TcSimplify.extractResults is quite difficult to get right.
  This is another attempt; finally I think I have it.
  
  Strangely enough, it's only Sergey's DoCon program that shows up the
  bug, which manifested as a failure in the Simplifier
  
          lookupRecBndr $dGCDRing{v a1Lz} [lid]
  
  But it was due to extractResults producing multiple bindings for
  the same dictionary.
  
  Please merge this to the stable branch (after previous patches to
  TcSimplify though).
  
  

    M ./compiler/typecheck/TcSimplify.lhs -43 +35