anchor.diff:  
     haskellPackages = haskellPackages_ghc6104;
   
  +  /*
     haskellPackages_ghc642 = import ./haskell-packages.nix {
       inherit pkgs;
       ghc = import ../development/compilers/ghc/6.4.2.nix {
  
positive.code:       };
      };
    });
  
    haskellPackages_ghc6101 = import ./haskell-packages.nix {
      inherit pkgs;
  
negative.code: 
    #ghc = haskellPackages.ghc;
  
    /*
    ghc642Binary = lowPrio (import ../development/compilers/ghc/6.4.2-binary.nix {
      inherit fetchurl stdenv ncurses gmp;
      readline = if stdenv.system == "i686-linux" then readline4 else readline5;
      perl = perl58;
    });
    */
  
    ghc6101Binary = lowPrio (import ../development/compilers/ghc/6.10.1-binary.nix {
      inherit fetchurl stdenv perl ncurses gmp libedit;
  