anchor.diff:    ] ++ lib.optionals pythonSupport [
       libxml2.py
       python
  +    ncurses
     ] ++ lib.optionals cryptoSupport [
       libgcrypt
     ];
  
positive.code: { lib
  , stdenv
  , fetchurl
  , fetchpatch
  , pkg-config
  , libxml2
  , findXMLCatalogs
  , gettext
  , python
  , libgcrypt
  , cryptoSupport ? false
  , pythonSupport ? stdenv.buildPlatform == stdenv.hostPlatform
  
negative.code: 
  stdenv.mkDerivation rec {
    pname = "libxslt";
    version = "1.1.35";
  
    outputs = [ "bin" "dev" "out" "man" "doc" ] ++ lib.optional pythonSupport "py";
  
    src = fetchurl {
      url = "mirror://gnome/sources/${pname}/${lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
      sha256 = "gkfzPpqHLGrIWapFAYvExNALl+L+rJ7rwQyTzh803Xk=";
    };
  
    nativeBuildInputs = [
      pkg-config
  