flutter_l10n Free

A Mason brick for generating a Flutter localization package using Slang v4, with type-safe translations, per-feature l10n support, and Indonesian pluralization.

Version: 2.0.0

Variables

Variable	Type	Default	Description
appName	string	MyApp	Application name for package naming
prefix	string	App	Prefix for generated locale enum (e.g. AppLocale)
isForMonorepo	boolean	true	Whether this package will be part of a monorepo structure

Usage

Interactive

archipelago generate flutter_l10n

Non-interactive (CI)

archipelago generate flutter_l10n --config my_config.json

Config Template

{
  "@appName": "Application name for package naming",
  "appName": "MyApp",
  "@prefix": "Prefix for generated locale enum",
  "prefix": "App",
  "@isForMonorepo": "Whether this package will be part of a monorepo structure",
  "isForMonorepo": true
}

Generated Structure

shared/
└── locale_core/
    ├── l10n/                                # Translation source files
    │   ├── general/
    │   │   ├── general_en.i18n.json         # English translations
    │   │   └── general_id.i18n.json         # Indonesian translations
    │   └── feedback/
    │       ├── dialog_en.i18n.json
    │       ├── error_en.i18n.json
    │       └── success_en.i18n.json
    ├── lib/
    │   ├── locale_core.dart                 # Barrel (re-exports slang_flutter + translations)
    │   └── src/
    │       ├── translations/
    │       │   └── translations.g.dart      # Generated by slang
    │       └── utils/
    │           ├── extensions.dart           # Locale-aware formatting
    │           ├── resolver.dart             # Indonesian pluralization rules
    │           └── utils.dart               # Barrel export
    ├── slang.yaml                           # Slang configuration
    ├── build.yaml                           # build_runner config (sources: l10n/**)
    ├── pubspec.yaml
    └── README.md

Key Features

• Slang v4 — Type-safe, compile-time checked translations with namespace support
• Dual generation — dart run slang (standalone) or via slang_build_runner with build_runner
• Namespaces — Organize translations by domain (general, feedback, etc.)
• Indonesian support — Custom pluralization resolver for Bahasa Indonesia
• Per-feature l10n — Feature modules (auth, home) can have their own slang.yaml with scoped translations (e.g. context.authL10n)

Slang Configuration

The slang.yaml configures how translations are generated:

base_locale: en
enum_name: AppLocale              # Generated from prefix variable
class_name: Translations
translate_var: l10n               # Access via context.l10n
input_directory: l10n
output_directory: lib/src/translations
namespaces: true
flutter_integration: true

Per-Feature Translations

Feature modules can have their own translations. Each feature gets its own slang.yaml:

# features/auth/auth_impl/slang.yaml
translate_var: authL10n           # context.authL10n
enum_name: AuthLocale
class_name: AuthTranslations

Shell pages sync the global locale to feature-scoped translations:

final authLocale = AuthLocale.values.firstWhere(
  (l) => l.languageTag == locale.languageTag,
  orElse: () => AuthLocale.en,
);
await LocaleSettings.setLocale(authLocale);

Dependencies

• slang ^4.14.0 — Core translation engine
• slang_flutter ^4.14.0 — Flutter integration (TranslationProvider, LocaleSettings)
• slang_build_runner ^4.14.0 (dev) — build_runner integration

Build Configuration

The build.yaml must include sources: ["l10n/**"] so build_runner can find translation files outside lib/:

targets:
  $default:
    sources:
      - "l10n/**"
      - "lib/**"
    builders:
      slang_build_runner:
        options:
          input_directory: l10n
          output_directory: lib/src/translations