describe('TaskEither complex pipeline', () => {
  it('processes valid users', async () => {
    const users: User[] = [
      { id: 1, email: 'alice@example.com', age: 25 },
      { id: 2, email: 'bob@example.com', age: 35 },
      { id: 3, email: 'charlie@example.com', age: 55 },
    ]

    const result = await processUsers(users)()
    expect(result._tag).toBe('Right')
    if (result._tag === 'Right') {
      expect(result.right).toEqual([
        { id: 1, email: 'alice@example.com', ageGroup: 'young' },
        { id: 2, email: 'bob@example.com', ageGroup: 'middle' },
        { id: 3, email: 'charlie@example.com', ageGroup: 'senior' },
      ])
    }
  })

  it('fails on invalid user', async () => {
    const users: User[] = [
      { id: 1, email: 'alice@example.com', age: 25 },
      { id: 2, email: 'invalid-email', age: 16 },
    ]

    const result = await processUsers(users)()
    expect(result._tag).toBe('Left')
    if (result._tag === 'Left') {
      expect(result.left.length).toBeGreaterThan(0)
    }
  })
})