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

[Mateusz Czaplinski]

On Mon, Jun 6, 2016 at 11:30 AM, Kamil Chmielewski <kamil.chm at gmail.com> wrote:
> The '_pkgs : with _pkgs; {' part comes from
> https://nixos.org/wiki/Howto_keep_multiple_packages_up_to_date_at_once.

Yes, I've noticed. I know it works, and I'm very grateful to you for
publicizing your solution in one of the "declarative user config"
issues, so that I could adopt it. But I'd like to understand what it
does and how it works. I've seen packageOverrides written in this way,
as will as in other ways (e.g. the Nix manual uses 'rec' and doesn't
use 'with'). I'd like to understand what's going on here, why is it
needed, why sometimes one form sometimes other, and how and when to
use one or the other. I tried to explore it with the manuals in hand,
but to no success. So I thought maybe someone could help me with this?

As to other perceived complications (esp. 'buildEnv'), I seem to have
worked through them already,

Thanks,
/Mateusz.