NixOS doesn't actually use callPackage. it uses lib.evalModules. The fact there is a difference between how NixOS is evaluated, vs how Nixpkgs is evaluated is

NixOS doesn't actually use callPackage. it uses lib.evalModules. The fact there is a difference between how NixOS is evaluated, vs how Nixpkgs is evaluated is something I actually find quite annoying. Whilst nixpkgs is all about functions and dependency injection, NixOS is all about merging dictionaries. Here is some context, with corresponding criticsm by the person behind Guix, which might give some interesting insights https://discourse.nixos.org/t/best-resources-for-learning-about-the-nixos-module-system/1177/4 https://discourse.nixos.org/t/best-resources-for-learning-ab...