anchor.diff:  
     nativeBuildInputs = [ dune-configurator pkg-config ];
     propagatedBuildInputs = [
  -    cstruct eqaf
  +    cstruct eqaf bigarray-compat
     ] ++ lib.optionals withFreestanding [
       ocaml-freestanding
     ];
  
positive.code: { lib, fetchurl, buildDunePackage, ounit, cstruct, dune-configurator, eqaf, pkg-config
  , withFreestanding ? false
  , ocaml-freestanding
  }:
  
negative.code:   minimumOCamlVersion = "4.08";
  
    pname = "mirage-crypto";
    version = "0.10.0";
  
    src = fetchurl {
      url = "https://github.com/mirage/mirage-crypto/releases/download/v${version}/mirage-crypto-v${version}.tbz";
      sha256 = "20915c53ddb658c53f588c414f13676bc8ad3cd734d9ed909225ea080dd8144d";
    };
  
    useDune2 = true;
  