[Nix-dev] How to use .nixpkgs/config.nix?

[Mateusz Czaplinski]

Hi!
I'd like to have my home dir & per-user set of packages managed
declaratively. I've seen some suggestions, from which I seem to
believe I could try to do that using .nixpkgs/config.nix. Is that
possible? how could I do that the simplest way?

I'm new to Nix/NixOS. I've set up a simple NixOS install on a laptop,
but I'm having trouble understanding how to use local config.nix vs.
global configuration.nix. The manuals seem very sparse on config.nix
to me. The config.nix from Kamil Chmielewski [1] seems somewhat
acceptable to me at first sight, but I still don't get why config.nix
seems so much more complicated than configuration.nix? Is it possible
to make it simpler?

I'd like to start with a simplest config which would let me add some
packages which would be available for my user immediately after login
(also when logging in straight to an X session).

[1] https://github.com/NixOS/nixpkgs/issues/1750#issuecomment-186385710

Thanks,
/Mateusz Czapliński.