anchor.diff:  
       # BEAM
       beam.interpreters.erlangR19
  +    # FIXME: erlang
   
       # C/C++
       cc
  
positive.code:     nodejs = pkgs.nodejs-7_x;
      nodePackages = pkgs.nodePackages //
        pkgs.callPackage ./pkgs/development/node-packages {
          inherit pkgs nodejs;
        };
      # ocaml = pkgs.ocaml_4_03;
      # TODO: postgresql = pks.postgresql96;
  
negative.code:     # json-minify
      # jsonlint
      resume-cli
      # speed-test
      vmd
    ]) ++ (with pkgs.python27Packages; [
      pywatchman
    ]) ++ (with pkgs.python35Packages; [
      pip
      pygments
      setuptools
  