anchor.diff:  { monolithic ? true # build monolithic Quassel
   , daemon ? false # build Quassel daemon
   , client ? false # build Quassel client
  -, kde ? true # enable KDE integration
  +, withKDE ? true # enable KDE integration
   , ssl ? true # enable SSL support
   , previews ? false # enable webpage previews on hovering over URLs
  -, stdenv, fetchurl, cmake, qt4, kdelibs ? null, automoc4 ? null, phonon ? null }:
  -
  -assert kde -> kdelibs != null && automoc4 != null && phonon != null;
  +, stdenv, fetchurl, cmake, qt4, kdelibs, automoc4, phonon }:
   
   let
     edf = flag: feature: [("-D" + feature + (if flag then "=ON" else "=OFF"))];
  
positive.code:     ++ edf monolithic "WANT_MONO"
      ++ edf daemon "WANT_CORE"
      ++ edf client "WANT_QTCLIENT"
      ++ edf kde "WITH_KDE"
      ++ edf ssl "WITH_OPENSSL"
      ++ edf previews "WITH_WEBKIT"  ;
  
  
negative.code:   };
  
    buildInputs = [ cmake qt4 ]
      ++ lib.optional withKDE kdelibs
      ++ lib.optional withKDE automoc4
      ++ lib.optional withKDE phonon;
  
    cmakeFlags = [
      "-DWITH_DBUS=OFF"
  