anchor.diff:  , fetchurl
   , bzip2
   , freetype
  -, graphviz
   , ghostscript ? null
   , libjpeg
   , libpng
  
positive.code: 
    propagatedBuildInputs =
      [ bzip2 freetype libjpeg libpng libtiff libxml2 zlib librsvg
      libtool jasper libX11 ] ++ stdenv.lib.optional (ghostscript != null && stdenv.system != "x86_64-darwin") ghostscript;
  
    buildInputs = [ tetex graphviz ];
  
    postInstall = ''(cd "$out/include" && ln -s ImageMagick* ImageMagick)'';
  
  
negative.code:     sha256 = "1bpj8676mph5cvyjsdgf27i6yg2iw9iskk5c69mvpxkyawgjw1vg";
    };
  
    enableParallelBuilding = true;
  
    preConfigure = if tetex != null then
      ''
        export DVIDecodeDelegate=${tetex}/bin/dvips
  