anchor.diff:      "--disable-profiling"
       "--enable-optimization"
       "--disable-precompiled-headers"
  -    (enFlag "qt" (qt5 != null) null)
  +    "--${boolEn (qt5 != null)}-qt"
       "--disable-static-qt"
       "--enable-magic"
  -    (wtFlag "flac" (flac != null) null)
  +    "--${boolWt (flac != null)}-flac"
       "--without-curl"
  -    (wtFlag "boost" (boost != null) null)
  -    (wtFlag "boost-libdir" (boost != null) "${boost.lib}/lib")
  +    "--${boolWt (boost != null)}-boost"
  +    "--${boolWt (boost != null)}-boost-libdir${
  +      boolString (boost != null) "=${boost.lib}/lib" ""}"
       "--with-gettext"
       "--without-tools"
     ];
  
positive.code:   '';
  
    installPhase = ''
      ./drake install -j $NIX_BUILD_CORES
    '';
  
    passthru = {
  
negative.code: 
  let
    inherit (stdenv.lib)
      boolEn
      boolString
      boolWt
      optionals;
  in
  stdenv.mkDerivation rec {
    name = "mkvtoolnix-9.4.0";
  
    src = fetchurl {
      url = "https://mkvtoolnix.download/sources/${name}.tar.xz";
      multihash = "Qmd5dq1S9xeXHPmnaH1e86yCWDJ84p92eF7H5RGnd3LXrm";
      sha256 = "af633768ac3ca193070c76c93bbf496b41e451d1652e1d3d6fd4c20361e56265";
    };
  
    nativeBuildInputs = [
  