{
  config,
  lib,
  ...
}: let
  inherit (lib) types mkOption;
in {
  options = {
    module.locale = mkOption {
      type = types.strMatching "[a-z]{2}_[A-Z]{2}\\.UTF-8";
      default = "en_US.UTF-8";
      description = "set locale";
    };
  };
  config = {
    i18n = let
      inherit (config.module) locale;
    in {
      defaultLocale = locale;
      extraLocaleSettings = {
        LC_ADDRESS = locale;
        LC_COLLATE = "en_US.UTF-8";
        LC_CTYPE = locale;
        LC_IDENTIFICATION = locale;
        LC_MEASUREMENT = locale;
        LC_MESSAGES = locale;
        LC_MONETARY = locale;
        LC_NAME = locale;
        LC_NUMERIC = locale;
        LC_PAPER = locale;
        LC_TELEPHONE = locale;
        LC_TIME = locale;
      };
    };
  };
}