{ config, pkgs, ... }:
let
  unstableTarball =
    fetchTarball
      https://github.com/NixOS/nixpkgs/archive/nixos-unstable.tar.gz;  
in
{
  nixpkgs.config = {
    packageOverrides = pkgs: {
      unstable = import unstableTarball {
        config = config.nixpkgs.config;
      };
    };
  };

  environment.systemPackages = with pkgs; [
    curl
    wget
  ];
}
