TypeScript

// أنواع مخصصة ومجمعة
interface User {
  id: string;
  name: string;
  email: string;
  role: 'admin' | 'editor' | 'viewer';
  preferences?: {
    theme: 'dark' | 'light';
    language: string;
  };
}

// أصناف شاملة (Generics)
class Repository<T extends { id: string }> {
  private items: T[] = [];

  async fetchAll(url: string): Promise<T[]> {
    const response = await fetch(url);
    if (!response.ok) {
      throw new RepositoryError(`Fetch failed: ${response.statusText}`);
    }
    const data = await response.json() as T[];
    this.items.push(...data);
    return data;
  }

  findById(id: string): T | undefined {
    return this.items.find(item => item.id === id);
  }
}

// أنواع شرطية وMap Types
type ApiResponse<T> = 
  | { status: 'success'; data: T }
  | { status: 'error'; message: string };

type ReadonlyUser = Readonly<User>;
type UserKeys = keyof User;
type UserEmail<User> = User extends { email: infer E } ? E : never;