anchor.diff:      rtiff = [ pkgs.libtiff.dev ];
       runjags = [ pkgs.jags ];
       RVowpalWabbit = [ pkgs.zlib.dev pkgs.boost ];
  -    rzmq = [ pkgs.zeromq ];
  +    rzmq = [ pkgs.zeromq pkgs.pkgconfig ];
  +    clustermq = [ pkgs.zeromq ];
       SAVE = [ pkgs.zlib pkgs.bzip2 pkgs.icu pkgs.lzma pkgs.pcre ];
       sdcTable = [ pkgs.gmp pkgs.glpk ];
       seewave = [ pkgs.fftw.dev pkgs.libsndfile.dev ];
  
positive.code:         '';
      });
  
      Cairo = old.Cairo.overrideDerivation (attrs: {
        NIX_LDFLAGS = "-lfontconfig";
      });
  
negative.code:     nat = [ pkgs.which ];
      nat_templatebrains = [ pkgs.which ];
      pbdZMQ = lib.optionals stdenv.isDarwin [ pkgs.darwin.binutils ];
      clustermq = [  pkgs.pkgconfig ];
      RMark = [ pkgs.which ];
      RPushbullet = [ pkgs.which ];
      RcppEigen = [ pkgs.libiconv ];
  