anchor.diff:  
     rtpPath = ".";
   
  -  nativeImpl = packages:
  -  (let
  +  # Generates a packpath folder as expected by vim
  +  packDir = packages:
  +  let
       # dir is "start" or "opt"
       linkLuaPlugin = plugin: packageName: dir: ''
         mkdir -p $out/pack/${packageName}/${dir}/${plugin.pname}/lua
  
positive.code:       ++ [
          "mkdir -p $out/pack/${packageName}/start/__python3_dependencies"
          "ln -s ${python3Env}/${python3Env.sitePackages} $out/pack/${packageName}/start/__python3_dependencies/python3"
        ]
      );
      packDir = (packages:
        stdenv.mkDerivation {
          name = "vim-pack-dir";
          src = ./.;
          installPhase = lib.concatStringsSep "\n" (lib.flatten (lib.mapAttrsToList packageLinks packages));
          preferLocalBuild = true;
        }
      );
    in
    ''
      set packpath^=${packDir packages}
      set runtimepath^=${packDir packages}
    '');
  
    /* Generates a vimrc string
  
  
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
  