anchor.diff:  { stdenv, fetchurl, which, ocsigen_server, ocsigen_deriving, ocaml, camlp4,
     js_of_ocaml, lwt_react, cryptokit,
     ipaddr, ocamlnet, lwt_ssl, ocaml_pcre,
  -  opam, ppx_tools, ppx_deriving, findlib
  +  opaline, ppx_tools, ppx_deriving, findlib
   , js_of_ocaml-ocamlbuild, js_of_ocaml-ppx, js_of_ocaml-ppx_deriving_json
   , js_of_ocaml-lwt
   , js_of_ocaml-tyxml
  
positive.code:     ppx_deriving
    ];
  
    installPhase = "opam-installer -i --prefix=$out --libdir=$OCAMLFIND_DESTDIR";
  
    setupHook = [ ./setup-hook.sh ];
  
  
negative.code: 
    patches = [ ./camlp4.patch ];
  
    buildInputs = [ ocaml which findlib js_of_ocaml-ocamlbuild js_of_ocaml-ppx_deriving_json opaline ppx_tools
      ocsigen_deriving
    ];
  
  