$ ls -lAF --color /nix/store
total 7355364
dr-xr-xr-x   1 root  root        6  1 Jan 1970  000bmy9k246z4bdywjkdi6hbybah9z0j-user/
dr-xr-xr-x   1 root  root        0  1 Jan 1970  000fdw5ijqc8nhgnnawfy11vxf1hi8rw-system-generators/
-r--r--r--   2 root  root     3599  1 Jan 1970  000hxqh70ck7sjhdvcn66zdsyp2yprpb-source.drv
-r--r--r--   2 root  root     2221  1 Jan 1970  000hy9cqahi1rwy2mx3yak8dq02pa5ih-gst-devtools-1.26.5-vendor.drv
-r--r--r--   2 root  root     3146  1 Jan 1970  000nzak0hrcsl7d2kf3l6d544p7kyrf2-crate-num_threads-0.1.7.tar.gz.drv
-r--r--r--   2 root  root     2223  1 Jan 1970  000skmmf43a4vnxnc775s78psjr96d54-001-fix-rpath.patch.drv
-r--r--r--   2 root  root     4493  1 Jan 1970  000x39hj0g61mkp15xgkz27j7fkzkh8h-CVE-2022-48174.patch.drv
-r--r--r--   2 root  root     3615  1 Jan 1970  0010xx2b5k2kxq0c5b3pwq3bby9rdk94-source.drv
-r--r--r--   2 root  root     3314  1 Jan 1970  0015pxy9jsaxgq729bfc5ikn9n1wssbi-gnome-font-viewer-48.0.drv
...

$ tree /nix/store/00zrahbb32nzawrmv9sjxn36h7qk9vrs-bash-5.2p37/
/nix/store/00zrahbb32nzawrmv9sjxn36h7qk9vrs-bash-5.2p37
├── bin
│   ├── bash
│   └── sh -> bash
└── lib
    └── bash
        ├── accept
        ├── basename
        ├── csv
        ├── cut
        ├── dirname
        ...
        ├── sync
        ├── tee
        ├── truefalse
        ├── tty
        ├── uname
        ├── unlink
        └── whoami

42

"foo"

true

~/.local/bin

[ "foo" "bar" 42 false ]

{ target = /etc/nixos; foo = 42; }

x: x + 1

{
  x = import ./number.nix;
}

{
  # negation
  truth = !false;

  # string and paths
  a_str = "Dirs" + ./.config/user;
  a_path = /etc + "/nixos";

  # list concatenation
  l = [ 1 2 3 ] ++ [ "four" "five"];
  
  # logical and, logical or
  m = true && false; n = true || false;
  
  # update attribute set
  s = { x = 1; } // { y = 1; x = 2; };
  
  # has attribute (attribute set member)
  h = { x = 42; } ? x;
}

{
  # available = builtins; 
  yes = true; no = false; nothing = null;
  system = builtins.currentSystem;
  epoch = builtins.currentTime;
  packages = builtins.storeDir;
  paths = builtins.nixPath;
  language = builtins.langVersion;
  version = builtins.nixVersion;
}

{
  d = builtins.readDir;
  f = builtins.readFile;
  e = builtins.getEnv "HOME";
  s = builtins.substring 0 3 "nixos";
  ...
}

{
  # numbers
  a = 1; f = 3.14;

  # strings
  text = "Hello Pi! ${f}";
  multi_line = ''
    Very long text ... with ${a}
  '';
  
  # paths
  x = /absolute/path/to
  y = ./relative/path
  z = ~/.config # path in home dir
}

{ lib, ... }:

{
  imports = [
    ./file.nix
  ];

  options = {
    magicNumber = lib.mkOption {
      type = lib.types.number;
      default = 3.14;
    };
  };

  config = {
    boot.loader.grub.enable = true;
  };
}

{ lib, ... }:

let
  preference = "GNOME";
in
{
  imports = [
    ./file.nix
  ];

  options = {
    desktop.style = lib.mkOption {
      type = lib.types.enum [ "Windows" "macOS" "GNOME" ];
      default = preference;
    };
  };
}

{
  console.keyMap = "it";

  services.xserver.xkb = {
    layout = "it";
    variant = "";
  };
}

{
  description = "Linux Day flake";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
  	nixos-hardware.url = "github:NixOS/nixos-hardware?ref=master";
  };

  outputs = { self, nixpkgs }: {
    nixosConfigurations = nixpkgs.lib.mapAttrs mkSystem systems;
  };
}

{
  description = "A simple Go package";
  inputs.nixpkgs.url = "nixpkgs/nixos-25.11";
  outputs = { self, nixpkgs }:
  {
    packages = forAllSystems (system:
      let
        pkgs = nixpkgsFor.${system};
      in
        ...
    );
  };
  devShells = forAllSystems (system:
    default = pkgs.mkShell {
      buildInputs = with pkgs; [ go gopls gotools go-tools ];
    };
  );
}

{
  environment = {
    localBinInPath = true; # ~/.local/bin in PATH
    systemPackages = with pkgs; [
      uv # install Pythons in user-space using uv
    ];
  };

  programs.nix-ld = {
    enable = true;
    libraries = with pkgs; [
      libelf
      libjpg
      libpng
    ];
  };
}

---
deadnix:
  extends: .nix
  script: nix run nixpkgs#deadnix -- --fail

statix:
  extends: .nix
  script: nix run nixpkgs#statix -- check

flake:
  extends: .nix
  script:
  - nix flake check
  - nix flake show

disko:
  extends: .nix
  script: nix run github:nix-community/disko/latest --
    --mode destroy,format,mount --dry-run --flake .#generic

tooling:
  extends: .megalinter
  variables:
    FLAVOR: documentation