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feat: Add explanation how arguments are passed to imports in imports

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Great documentation!

- I did not understand exactly at the begining how Nix passes arguments in the `imports` list. I made a small example section which describes the observed behavior.

I hope its correct. I think it greatly helps to understand how these things are called. Maybe there is a reference to this?

Do you know?
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docs/nixos-with-flakes/modularize-the-configuration.md
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@ -26,7 +26,36 @@ The Nix module system provides a parameter, `imports`, which accepts a list of `
> I only found a description of `imports` in [Nixpkgs-Unstable Official Manual - evalModules Parameters](https://nixos.org/manual/nixpkgs/unstable/#module-system-lib-evalModules-parameters): `A list of modules. These are merged together to form the final configuration.` It's a bit ambiguous...
With the help of `imports`, we can split `home.nix` and `configuration.nix` into multiple Nix modules defined in different `.nix` files.
With the help of `imports`, we can split `home.nix` and `configuration.nix` into multiple Nix modules defined in different `.nix` files. Lets look at an example module `packages.nix`:
```nix
{
config,
pkgs,
...
}: {
imports = [
(import ./special-fonts-1.nix {inherit config pkgs}) # (1)
./special-fonts-2.nix # (2)
];
fontconfig.enable = true;
}
```
This modules loads two other modules in the imports section, namely `special-fonts-1.nix` and `special-fonts-2.nix`. Both files are modules them self and look similar to this.
```nix
{ config, pkgs, ...}: {
# Configuration stuff ...
}
```
Both import statemnets above are equivalent in the parameters they receive:
- Statement `(1)` imports the function in `special-fonts-1.nix` and calls it by passing `{config = config; pkgs = pkgs}`. Basically using the return value of the call (another partial configuration [attritbute set]) inside the `imports` list.
- Statement `(2)` defines a path to a module, whose function Nix will load *automatically* when assembling the configuration `config`. It will pass all matching arguments from the function in `packages.nix` to the loaded function in `special-fonts-2.nix` which results in `import ./special-fonts-2.nix {config = config; pkgs = pkgs}`.
Here is a nice starter example of modularizing the configuration, Highly recommended: