anchor.diff:    # nixpkgs.config.allowBroken = true; # HACK
   
     nixpkgs.config.packageOverrides = pkgs: {
  +    camlp5 = pkgs.ocamlPackages.camlp5_6_strict;
       coq = pkgs.coq_8_6;
       erlang = pkgs.erlangR19;
       gcc = pkgs.gcc6;
       mono = pkgs.mono46;
       nodejs = pkgs.nodejs-7_x;
       ocaml = pkgs.ocaml_4_03;
  +    # TODO: postgresql = pks.postgresql96;
       protobuf = pkgs.protobuf3_1;
       # TODO: mysql = mysql57;
     };
  
positive.code: 
      # OCaml
      ocaml
      # TODO: ocamlPackages.ocamlbuild
      ocamlPackages.camlp5_6_strict
      opam
  
      # Protocol Buffers
  
negative.code:     # FIXME: graphicsmagick # NOTE: graphviz error
      # FIXME: imagemagick
      lame
      # FIXME: timidity
  
      # BEAM
  