code-style

Code Style

Critical Requirement

MUST run nix fmt <paths...> after making any changes to ensure consistent formatting.

Indentation

• Use 2 spaces for indentation
• No tabs allowed

Naming Conventions

Comments

• Minimal comments preferred
• Code should be self-explanatory
• Use comments to explain why, not what

# Good: explains why
# Workaround for upstream bug #1234
extraConfig = "...";

# Bad: describes what (obvious from code)
# Set extraConfig to the value
extraConfig = "...";

Imports

• Prefer relative imports: ./modules/foo.nix
• Group imports at the top of the file
• Use list format for multiple imports:

{
  imports = [
    ./hardware.nix
    ./services.nix
    ./networking.nix
  ];
}

Structured Data

When generating JSON, YAML, or other structured formats, define as Nix attribute sets and convert:

# Good: define as Nix, convert to JSON
environment.etc."config.json".text = builtins.toJSON {
  setting = "value";
  nested = { key = 123; };
};

# Avoid: inline JSON strings
environment.etc."config.json".text = ''
  {"setting": "value", "nested": {"key": 123}}
'';

Common Patterns

Module Structure

{
  config,
  lib,
  pkgs,
  ...
}:
let
  inherit (lib) mkEnableOption mkOption mkIf types;
  cfg = config.services.myService;
in
{
  options.services.myService = {
    enable = mkEnableOption "my service";
  };

  config = mkIf cfg.enable {
    # configuration here
  };
}

Let Bindings

let
  inherit (lib) mkIf mkEnableOption;
  cfg = config.myModule;
in
{
  # use cfg, mkIf, etc.
}