anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "furnace";
  -  version = "0.5.8";
  +  version = "0.6pre1";
   
     src = fetchFromGitHub {
       owner = "tildearrow";
       repo = "furnace";
       rev = "v${version}";
       fetchSubmodules = true;
  -    sha256 = "103ymd3wa1sfsr6qg15vpcs53j350i7zidv3azlf7cynk6k28xim";
  +    sha256 = "sha256-7MrzSC8PYQ4X8fyX1hB8mOoSCtLpY+o1x42v9HLdoao=";
     };
  -
  -  postPatch = ''
  -    # rtmidi is not used yet
  -    sed -i -e '/add_subdirectory(extern\/rtmidi/d' -e '/DEPENDENCIES_LIBRARIES rtmidi/d' CMakeLists.txt
  -  '';
   
     nativeBuildInputs = [
       cmake
  
positive.code:   ];
  
    buildInputs = [
      fmt_8
      libsndfile
      SDL2
      zlib
    ] ++ lib.optionals withJACK [
  
negative.code:     };
      tests.version = testers.testVersion {
        package = furnace;
      };
    };
  
  