anchor.diff:  { stdenv, fetchurl, cmake, lzma, boost, libdevil, zlib, p7zip
   , openal, libvorbis, glew, freetype, xlibs, SDL, mesa, binutils
   , asciidoc, libxslt, docbook_xsl, docbook_xsl_ns, curl, makeWrapper
  -, jdk ? null, python ? null
  +, jdk ? null, python ? null, systemd
   , withAI ? true # support for AI Interfaces and Skirmish AIs
   }:
   
  
positive.code: 
    buildInputs = [ cmake lzma boost libdevil zlib p7zip openal libvorbis freetype SDL 
      xlibs.libX11 xlibs.libXcursor mesa glew asciidoc libxslt docbook_xsl curl makeWrapper
      docbook_xsl_ns ]
      ++ stdenv.lib.optional withAI jdk
      ++ stdenv.lib.optional withAI python;
  
  
negative.code: 
    postInstall = ''
      wrapProgram "$out/bin/spring" \
        --prefix LD_LIBRARY_PATH : "${stdenv.gcc.gcc}/lib64:${stdenv.gcc.gcc}/lib::${systemd}/lib"
    '';
  
    meta = with stdenv.lib; {
  