~/.nixpkgs/config.nix

config.nix

{
  packageOverrides = pkgs:
    let
      haskell   = pkgs.haskellPackages_ghc704;
      emacs     = pkgs.emacs23Packages;
      lowPrio   = pkgs.lib.lowPrio;
      hiPrio    = pkgs.lib.hiPrio;

      # uhc     = haskell.uhc.override {useJSBackend = true; };
      uhc       = haskell.uhc; # js backend is enabled by default nowadays
      myTexLive = pkgs.texLiveAggregationFun {
                    paths = [ pkgs.texLive 
                              pkgs.texLiveExtra
                              pkgs.texLiveBeamer
                              pkgs.texLiveCMSuper ];
                  };
    in
    rec {
      mathijs = pkgs.buildEnv {
        ignoreCollisions = true;
        name = "mathijs";
        paths = [ haskell.haskellPlatform # _2011_2_0_1
                  haskell.ghcMod
                  haskell.hlint
                  uhc
                  pkgs.unison
                  pkgs.nodejs
                  pkgs.auctexWithPreview
                  pkgs.emacs
                  emacs.haskellMode
                  emacs.org
                  emacs.emacsw3m
                  pkgs.jruby165
                  pkgs.MPlayer
                  pkgs.nzbget
                  myTexLive
                  pkgs.jre
                  pkgs.graphviz
                  pkgs.youtubeDL
                  pkgs.aspell
                  pkgs.aspellDicts.en
                  pkgs.aspellDicts.nl
                  pkgs.openssl
                  pkgs.gnutls
                  haskell.lhs2tex
                  pkgs.nginx
                  pkgs.libcap_progs
                ];
      };
    };
}