anchor.diff:  
     src = fetchurl {
       url = "https://caml.inria.fr/pub/distrib/ocaml-${baseOcamlBranch}/ocaml-${baseOcamlVersion}.tar.gz";
  -    sha256 = "1x4sln131mcspisr22qc304590rvg720rbl7g2i4xiymgvhkpm1a";
  +    sha256 = "sha256-3Yi2OFvZLgrZInMuKMxoyHd4QXcOoAPCC9FS9dtEFc4=";
     };
   
     metaocaml = fetchurl {
  -    url = "http://okmij.org/ftp/ML/ber-metaocaml-107.tar.gz";
  -    sha256 = "0xy6n0yj1f53pk612zfmn49pn04bd75qa40xgmr0w0lzx6dqsfmm";
  +    url = "http://okmij.org/ftp/ML/ber-metaocaml-${metaocamlPatch}.tar.gz";
  +    sha256 = "sha256-hDb0w0ZCm0hCz8jktZKmr/7gPSfBoKPT/cc7sPjt0yE=";
     };
   
     x11env = buildEnv { name = "x11env"; paths = x11deps; };
  
positive.code:   x11inc = "${x11env}/include";
  
    prefixKey = "-prefix ";
    configureFlags = optionals useX11
      [ "-x11lib" x11lib
        "-x11include" x11inc
        "-flambda"
      ];
  
    dontStrip = true;
    buildInputs = [ ncurses ] ++ optionals useX11 x11deps;
  
negative.code:    x11deps = [ libX11 xorgproto ];
     inherit (lib) optionals;
  
     baseOcamlBranch  = "4.11";
     baseOcamlVersion = "${baseOcamlBranch}.1";
     metaocamlPatch   = "111";
  in
  
  stdenv.mkDerivation rec {
  