anchor.diff:  
     dirmngr = callPackage ../tools/security/dirmngr { };
   
  -  docbook2x = callPackage ../tools/typesetting/docbook2x { 
  +  docbook2x = callPackage ../tools/typesetting/docbook2x {
       inherit (perlPackages) XMLSAX XMLParser XMLNamespaceSupport;
       libiconv = if stdenv.isDarwin then libiconv else null;
     };
  
positive.code:   /*
    haskellPackages_ghcHEAD = lowPrio (import ./haskell-packages.nix {
      inherit pkgs;
      ghc = callPackage ../development/compilers/ghc/6.11.nix { 
        inherit (haskellPackages) happy alex; # hope these aren't required for the final version
        ghc = ghc6101Binary;    };
    });
  
negative.code:     system == "x86_64-darwin" ||
      system == "i686-darwin";
  
    mesa = callPackage ../development/libraries/mesa {
      lipo = if stdenv.isDarwin then darwinLipoUtility else null;
    };
  
    ming = callPackage ../development/libraries/ming { };
  
    mlt = callPackage ../development/libraries/mlt {
      qt = qt4;
    };
  
  