anchor.diff:  
       license = stdenv.lib.licenses.lgpl21;
   
  -    platforms = ocaml.meta.platforms or [];
  -
       maintainers = [ stdenv.lib.maintainers.gal_bolle ];
     };
  -})
  +}
  
positive.code: { stdenv, fetchurl, ocaml, findlib, which, ocsigen_server, ocsigen_deriving,
    js_of_ocaml, ocaml_react, ocaml_lwt, calendar, cryptokit, tyxml,
    ipaddr, ocamlnet, ocaml_ssl, ocaml_pcre, ocaml_optcomp,
    reactivedata, opam, ppx_tools, camlp4}:
  
  let ocamlVersion = (stdenv.lib.getVersion ocaml);
    in
  
  (
  assert stdenv.lib.versionAtLeast ocamlVersion "4";
  
  stdenv.mkDerivation rec
  {
    pname = "eliom";
    version = "5.0.0";
  
negative.code: 
    patches = [ ./camlp4.patch ];
  
    buildInputs = [ which ocaml_optcomp opam ppx_tools camlp4 ];
  
    propagatedBuildInputs = [ ocaml_lwt reactivedata tyxml ipaddr ocsigen_server ppx_deriving
                              ocsigen_deriving js_of_ocaml
                              calendar cryptokit ocamlnet ocaml_react ocaml_ssl ocaml_pcre ];
  
    preConfigure = stdenv.lib.optionalString (!stdenv.lib.versionAtLeast ocamlVersion "4.02") ''
        export PPX=false
  