international-types

import type { LocaleKeys, BaseLocale, Scopes, ScopedValue, CreateParams, ParamsObject } from 'international-types'; type AppLocale = { param: 'This is a {value}'; 'hello.people': 'Hello {name}! You are {age} years old.'; 'scope.nested.greeting': 'A nested greeting.'; }; function createI18nTypedT<Locale extends BaseLocale, Scope extends Scopes<Locale> | undefined>(scope?: Scope) { return function t<Key extends LocaleKeys<Locale, Scope>, Value extends ScopedValue<Locale, Scope, Key>>( key: Key, ...params: CreateParams<ParamsObject<Value>, Locale, Scope, Key, Value> ) { // In a real i18n library, this function would handle the actual translation lookup and interpolation. // For this example, we just log the key and params to demonstrate type safety. console.log(`Translating key: ${String(key)} with params: ${JSON.stringify(params[0]) || '{}'}`); // Example: Dummy return for a type-safe signature return `Translated: ${String(key)}` }; } const t = createI18nTypedT<AppLocale, undefined>(); t('param', { value: 'exampleValue' // 'value' is required and type-checked here }); t('hello.people', { name: 'John Doe', age: 30 // 'name' and 'age' are required and type-checked }); const scopedT = createI18nTypedT<AppLocale, 'scope.nested'>('scope.nested'); scopedT('greeting'); // Autocompletes to 'greeting' under 'scope.nested' // Example of intentionally incorrect usage (will cause TypeScript errors) // t('non.existent.key'); // t('param', { wrongParam: 'value' }); // t('hello.people', { name: 'Alice' }); // Missing 'age' parameter