anchor.diff:  
   with lib;
   let
  -  inherit (lib) mkOption mkIf optionals literalExpression;
  +  inherit (lib) mkOption mkIf optionals literalExpression optionalString;
     cfg = config.services.xserver.windowManager.xmonad;
   
     ghcWithPackages = cfg.haskellPackages.ghcWithPackages;
  
positive.code:               `additionalKeys`
                [ ( (mod4Mask,xK_r), compileRestart True)
                , ( (mod4Mask,xK_q), restart "xmonad" True ) ]
          '';
        };
  
  
negative.code:     in
        pkgs.runCommandLocal "xmonad" {
          nativeBuildInputs = [ pkgs.makeWrapper ];
        } (''
          install -D ${xmonadEnv}/share/man/man1/xmonad.1.gz $out/share/man/man1/xmonad.1.gz
          makeWrapper ${configured}/bin/xmonad $out/bin/xmonad \
        '' + optionalString cfg.enableConfiguredRecompile ''
            --set NIX_GHC "${xmonadEnv}/bin/ghc" \
        '' + ''
            --set XMONAD_XMESSAGE "${pkgs.xorg.xmessage}/bin/xmessage"
        '');
  
    xmonad = if (cfg.config != null) then xmonad-config else xmonad-vanilla;
  in {
  