10-option-patterns

10 - Option Patterns

This example demonstrates type-safe Option<T> and Result<T, E> usage in Haxe, compiled to idiomatic Elixir tuple patterns.

What this example demonstrates

• Repository APIs return Option<T> instead of nullable values.
• Service-layer flows compose Option and Result safely.
• ExUnit tests are authored in Haxe and compiled into Elixir tests.

Run

cd examples/10-option-patterns
haxe build.hxml
mix test

Key files

• Haxe sources:
  • examples/10-option-patterns/src_haxe/repositories/UserRepository.hx
  • examples/10-option-patterns/src_haxe/services/ConfigManager.hx
  • examples/10-option-patterns/src_haxe/services/NotificationService.hx
• Haxe-authored tests:
  • examples/10-option-patterns/test_haxe/repositories/UserRepositoryTest.hx
  • examples/10-option-patterns/test_haxe/services/ConfigManagerTest.hx
  • examples/10-option-patterns/test_haxe/services/NotificationServiceTest.hx
• Generated Elixir:
  • examples/10-option-patterns/lib/repositories/user_repository.ex
  • examples/10-option-patterns/lib/services/config_manager.ex
  • examples/10-option-patterns/lib/services/notification_service.ex

Haxe -> generated Elixir (shape)

Haxe (UserRepository.find):

public static function find(id: Int): Option<User> {
    if (id <= 0) return None;
    for (user in users) {
        if (user.id == id) return Some(user);
    }
    return None;
}

Generated Elixir shape:

def find(id) do
  if id <= 0 do
    {:none}
  else
    case Enum.reduce_while(users(), :__reflaxe_no_return__, fn user, _ ->
      if user.id == id, do: {:halt, {:__reflaxe_return__, {:some, user}}}, else: {:cont, :__reflaxe_no_return__}
    end) do
      {:__reflaxe_return__, value} -> value
      _ -> {:none}
    end
  end
end

Why this example exists

• It validates that high-level Haxe null-safety patterns map cleanly to BEAM tuple conventions.
• It gives a compact reference for teams adopting typed domain logic in Elixir without jumping directly into Phoenix complexity.

Next examples

• examples/11-domain-validation/README.md - typed domain validation and business rules.
• examples/06-user-management/README.md - Option/Result patterns in LiveView + Ecto app flow.
• examples/todo-app/README.md - full app with Presence/PubSub/UI runtime checks.