anchor.diff:      nloptr = [ pkgs.nlopt ];
       openssl = [ pkgs.openssl ];
       outbreaker = [ pkgs.gsl ];
  +    pander = [ pkgs.pandoc pkgs.which ];
       pbdMPI = [ pkgs.openmpi ];
       pbdNCDF4 = [ pkgs.netcdf ];
       pbdPROF = [ pkgs.openmpi ];
  
positive.code:     "PairViz" # requires graph
      "pamm" # requires nlopt
      "PANDA" # requires GO.db
      "pander" # build is broken
      "panelAR" # requires nlopt
      "papeR" # requires nlopt
      "parboost" # requires nlopt
  
negative.code:     RcppZiggurat = [ pkgs.gsl ];
      rgdal = [ pkgs.proj pkgs.gdal ];
      rgeos = [ pkgs.geos ];
      rggobi = [ pkgs.ggobi pkgs.gtk2 pkgs.libxml2 ];
      rgl = [ pkgs.mesa pkgs.x11 ];
      Rglpk = [ pkgs.glpk ];
      RGtk2 = [ pkgs.gtk2 ];
      Rhpc = [ pkgs.zlib pkgs.bzip2 pkgs.icu pkgs.lzma pkgs.openmpi pkgs.pcre ];
      ridge = [ pkgs.gsl ];
  