anchor.diff:  
     mesonFlags = [
       "-Dgtk_doc=${if stdenv.isDarwin then "false" else "true"}"
  -    "-Dlibthai=disabled" # Not packaged in Nixpkgs
     ] ++ stdenv.lib.optionals stdenv.isDarwin [
       "-Dxft=disabled"  # only works with x11
     ];
  
positive.code:   ];
    buildInputs = [
      fribidi
    ] ++ optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [
      ApplicationServices
      Carbon
  
negative.code: { stdenv, fetchurl, fetchpatch, pkgconfig, cairo, harfbuzz
  , libintl, libthai, gobject-introspection, darwin, fribidi, gnome3
  , gtk-doc, docbook_xsl, docbook_xml_dtd_43, makeFontsConf, freefont_ttf
  , meson, ninja, glib
  , x11Support? !stdenv.isDarwin, libXft
  