anchor.diff:    hackage2nix = self.callPackage ../tools/haskell/cabal2nix/hackage2nix.nix {};
     distribution-nixpkgs = self.callPackage ../tools/haskell/cabal2nix/distribution-nixpkgs.nix {};
   
  -  # https://github.com/urs-of-the-backwoods/HGamer3D/issues/7
  -  HGamer3D-Bullet-Binding = dontDistribute super.HGamer3D-Bullet-Binding;
  -  HGamer3D-Common = dontDistribute super.HGamer3D-Common;
  -  HGamer3D-Data = markBroken super.HGamer3D-Data;
  -
     # https://github.com/ndmitchell/shake/issues/206
     # https://github.com/ndmitchell/shake/issues/267
     shake = overrideCabal super.shake (drv: { doCheck = !pkgs.stdenv.isDarwin && false; });
  
positive.code: 
    # https://github.com/k0ral/hbro-contrib/issues/1
    hbro-contrib = dontDistribute super.hbro-contrib;
  
    # https://github.com/aka-bash0r/multi-cabal/issues/4
    multi-cabal = markBroken super.multi-cabal;
  
    # Elm is no longer actively maintained on Hackage: https://github.com/NixOS/nixpkgs/pull/9233.
    Elm = markBroken super.Elm;
  
negative.code:   apiary-session = dontCheck super.apiary-session;
    apiary-websockets = dontCheck super.apiary-websockets;
  
    # https://github.com/alephcloud/hs-configuration-tools/issues/40
    configuration-tools = dontCheck super.configuration-tools;
  
    # Test suite wants to connect to $DISPLAY.
    hsqml = dontCheck (super.hsqml.override { qt5 = pkgs.qt53; });
  
    # HsColour: Language/Unlambda.hs: hGetContents: invalid argument (invalid byte sequence)
    unlambda = dontHyperlinkSource super.unlambda;
  
    # https://github.com/PaulJohnson/geodetics/issues/1
    geodetics = dontCheck super.geodetics;
  