A little lost on flakes and overlays and how to incorporate them

[waffle8946]

A quick explanation here:

Import but don’t import your NixOS modules

The import keyword simply takes the contents of another file and drops it in-place where you import-ed, which is why using import messes up location info. Using your example, if you set something like _file = ./greet.nix; in your greet.nix you would get the correct location information. It’s not a pattern I’d recommend often, but it’s good to know about, especially as location information is also used in error messages.

But the simplest answer is: because you don’t need to use import (the nix builtin keyword) when you have the far more expressive imports (attribute used by the module system). They do different things, but with all the functionality provided by nixpkgs, I’ve not needed to use import in my config at all…