anchor.diff:        ++ [
           "mkdir -p $out/pack/${packageName}/start/__python3_dependencies"
           "ln -s ${python3Env}/${python3Env.sitePackages} $out/pack/${packageName}/start/__python3_dependencies/python3"
  -      ]
  -    );
  -    packDir = (packages:
  +      ];
  +  in
         stdenv.mkDerivation {
           name = "vim-pack-dir";
           src = ./.;
           installPhase = lib.concatStringsSep "\n" (lib.flatten (lib.mapAttrsToList packageLinks packages));
           preferLocalBuild = true;
  -      }
  -    );
  -  in
  +    };
  +
  +  nativeImpl = packages:
     ''
       set packpath^=${packDir packages}
       set runtimepath^=${packDir packages}
  -  '');
  +  '';
   
     /* Generates a vimrc string
   
  
positive.code: 
    rtpPath = ".";
  
    nativeImpl = packages:
    (let
      # dir is "start" or "opt"
      linkLuaPlugin = plugin: packageName: dir: ''
        mkdir -p $out/pack/${packageName}/${dir}/${plugin.pname}/lua
  
negative.code:       then linkLuaPlugin pluginPath
        else linkVimlPlugin pluginPath;
  
      packageLinks = packageName: {start ? [], opt ? []}:
      let
        # `nativeImpl` expects packages to be derivations, not strings (as
        # opposed to older implementations that have to maintain backwards
  