anchor.diff:  
       "opengles=0"
       "hss1394=0"
  -    (scFlag "hid" (libusb != null))
  -    (scFlag "bulk" (libusb != null))
  -    (scFlag "mad" (libmad != null))
  +    "hid=${bool01 (libusb != null)}"
  +    "bulk=${bool01 (libusb != null)}"
  +    "mad=${bool01 (libmad != null)}"
       "coreaudio=0"
       "mediafoundation=0"
       "ipod=0"
       "vinylcontrol=1"
  -    (scFlag "vamp" (vamp.vampSDK != null))
  -    (scFlag "modplug" (libmodplug != null))
  -    (scFlag "faad" (faad2 != null))
  -    (scFlag "wv" (wavpack != null))
  +    "vamp=${bool01 (vamp.vampSDK != null)}"
  +    "modplug=${bool01 (libmodplug != null)}"
  +    "faad=${bool01 (faad2 != null)}"
  +    "wv=${bool01 (wavpack != null)}"
       "color=0"
       "asan=0"
       "perftools=0"
  
positive.code:     "verbose=0"
      "profiling=0"
      "test=0"
      (scFlag "shoutcast" (libshout != null))
      (scFlag "opus" (opus != null))
      (scFlag "ffmpeg" (ffmpeg_2 != null))
      "optimize=portable"
      "autodjcrates=1"
      "macappstore=0"
  
negative.code: }:
  
  let
    inherit (lib)
      bool01;
  in
  stdenv.mkDerivation rec {
    name = "mixxx-2.0.0";
  
    src = fetchurl {
      url = "https://downloads.mixxx.org/${name}/${name}-src.tar.gz";
      sha256 = "e1b8f33bba35046608578095ed3209967034579252d84c99e6bc03ec030f676d";
    };
  
    nativeBuildInputs = [
  