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: }:
  
  let
    inherit (stdenv.lib)
      scFlag;
  in
  
  stdenv.mkDerivation rec {
    name = "mixxx-${version}";
    version = "2.0.0";
  
    src = fetchurl {
      url = "https://downloads.mixxx.org/${name}/${name}-src.tar.gz";
      sha256 = "0vb71w1yq0xwwsclrn2jj9bk8w4n14rfv5c0aw46c11mp8xz7f71";
    };
  
    nativeBuildInputs = [
  
negative.code:     runHook 'postInstall'
    '';
  
    meta = with lib; {
      description = "Digital DJ mixing software";
      homepage = "http://mixxx.org/";
      license = licenses.gpl2Plus;
  