sealed trait PasswordError

object PasswordError{
  case class TooShort(required: Int) extends PasswordError
  case class ToesNotContain(chars: String) extends PasswordError
}

sealed trait LoginError

object LoginError{
  case class TooLong(maxLength: Int) extends LoginError
  case object BadFormat extends LoginError
}

def validateLogin(login: String): ZIO[HasLoginConfig, LoginError, Unit]
def validatePassword(pass: String): ZIO[HasPasswordConfig, PasswordError, Unit]

def validateUser(user: User) = 
  validateLogin(user.login) *> validatePassword(user.pass)

// ZIO[
  HasLoginConfig & HasPasswordConfig, 
  LoginError | PasswordError
, Unit]