anchor.diff:      cd "$NIX_BUILD_TOP"
   
       emacs --batch -Q \
  -        -L "$melpa/package-build" \
  +        -L "$NIX_BUILD_TOP/package-build" \
           -l "$melpa2nix" \
           -f melpa2nix-build-package \
           $ename $version
  
positive.code:       cp "$recipe" "$NIX_BUILD_TOP/recipes/$ename"
      fi
  
      ln -s "$melpa/package-build" "$NIX_BUILD_TOP/package-build"
  
      mkdir -p "$NIX_BUILD_TOP/packages"
    '';
  
negative.code:     then pname
      else ename;
  
    packageBuild = fetchFromGitHub {
      owner = "melpa";
      repo = "package-build";
      rev = "0a22c3fbbf661822ec1791739953b937a12fa623";
      sha256 = "0dpy5p34il600sc8ic5jdgb3glya9si3lrvhxab0swks8fdydjgs";
    };
  
    elpa2nix = ./elpa2nix.el;
  