---

name: nix-option-types description: "Nix module option types and definition patterns. Use when defining options with mkOption, choosing types, or creating submodules."

Option Types

Prefer Helpers When Available

Basic Types

Copyoptions = {
  # Boolean (use mkEnableOption for enable flags)
  enable = mkEnableOption "feature";

  # String
  name = mkOption {
    type = types.str;
    default = "default";
    description = "The name";
  };

  # Integer
  count = mkOption {
    type = types.int;
    default = 1;
  };

  # Port (validated 1-65535)
  port = mkOption {
    type = types.port;
    default = 8080;
  };

  # Path
  configPath = mkOption {
    type = types.path;
    default = ./config.yaml;
  };

  # Package
  package = lib.mkPackageOption pkgs "myPackage" { };
};

Collection Types

Copyoptions = {
  # List of strings
  args = mkOption {
    type = types.listOf types.str;
    default = [ ];
  };

  # Attribute set of strings
  env = mkOption {
    type = types.attrsOf types.str;
    default = { };
  };

  # Enum (one of values)
  level = mkOption {
    type = types.enum [ "debug" "info" "error" ];
    default = "info";
  };

  # Nullable
  optional = mkOption {
    type = types.nullOr types.str;
    default = null;
  };

  # Either type
  portOrSocket = mkOption {
    type = types.either types.port types.path;
  };
};

Submodule Pattern

Copyoptions.services = mkOption {
  type = types.attrsOf (types.submodule {
    options = {
      enable = mkEnableOption "service";
      port = mkOption {
        type = types.port;
        default = 8080;
      };
    };
  });
  default = { };
};

# Usage:
config.namespace.services.myService = {
  enable = true;
  port = 9000;
};

mkPackageOption

Copy# Simple
package = lib.mkPackageOption pkgs "git" { };

# Nested package path
package = lib.mkPackageOption pkgs "nodePackages" {
  default = [ "typescript" ];
};