anchor.diff:  args: with args; with pkgs;
   let
     inherit (pkgs) stdenv fetchurl subversion;
  -  config = param: getConfig [ "git" param ];
   in
   rec {
   
  
positive.code:       asciidoc texinfo xmlto docbook2x
        docbook_xsl docbook_xml_dtd_45 libxslt
        cpio tcl tk makeWrapper subversion autoconf;
      svnSupport = config "svnSupport" false; # for git-svn support
      guiSupport = config "guiSupport" false;
      perlLibs = [perlPackages.LWP perlPackages.URI perlPackages.TermReadKey subversion];
    };
  
  
negative.code:     inherit fetchurl stdenv curl openssl zlib expat perl python gettext gnugrep
        asciidoc texinfo xmlto docbook2x docbook_xsl docbook_xml_dtd_45 libxslt
        cpio tcl tk makeWrapper subversion;
      svnSupport = false;		# for git-svn support
      guiSupport = false;		# requires tcl/tk
      sendEmailSupport = false;	# requires plenty of perl libraries
      perlLibs = [perlPackages.LWP perlPackages.URI perlPackages.TermReadKey];
      smtpPerlLibs = [
        perlPackages.NetSMTP perlPackages.NetSMTPSSL
  