15-phoenix-chat-haxe-first

15 - Phoenix Chat (Haxe-First)

Realtime chat example where the server module source-of-truth is Haxe, compiled to Phoenix LiveView + Presence.

This example is the Haxe-first counterpart to examples/12-phoenix-chat/:

• 12-phoenix-chat: hybrid adoption shape (feature logic in Haxe, core Phoenix wiring hand-authored Elixir)
• 15-phoenix-chat-haxe-first: app/router/live/presence authored in Haxe

What this example covers

• @:application supervision tree authored in Haxe
• @:router module-level typed routes authored in Haxe
• @:liveview callbacks and render in Haxe
• @:presence module in Haxe
• Haxe->JS client hook (AutoScroll) for LiveView
• TSX-style HXX templates (-D hxx_mode=tsx)

Run

cd examples/15-phoenix-chat-haxe-first
mix setup
mix phx.server

Open http://localhost:4000.

Tests

cd examples/15-phoenix-chat-haxe-first
mix test

The example includes a Haxe-authored ExUnit test:

• examples/15-phoenix-chat-haxe-first/src_haxe/test/live/ChatStateTest.hx

Source-of-truth split

Haxe-authored server modules

• examples/15-phoenix-chat-haxe-first/src_haxe/PhoenixChat.hx
  • @:application supervision tree (PhoenixChat.Application)
• examples/15-phoenix-chat-haxe-first/src_haxe/PhoenixChatRouter.hx
  • @:router module-level route DSL (PhoenixChatWeb.Router)
• examples/15-phoenix-chat-haxe-first/src_haxe/phoenix_chat_hx/live/AppLive.hx
  • @:liveview callbacks + render (PhoenixChatWeb.AppLive)
• examples/15-phoenix-chat-haxe-first/src_haxe/phoenix_chat_hx/presence/ChatPresence.hx
  • @:presence module (PhoenixChatWeb.Presence)

Elixir modules that still make sense to keep in Elixir

• Phoenix config/runtime wiring:
  • examples/15-phoenix-chat-haxe-first/config/*.exs
• Phoenix web infrastructure scaffold:
  • examples/15-phoenix-chat-haxe-first/lib/phoenix_chat_web/endpoint.ex
  • examples/15-phoenix-chat-haxe-first/lib/phoenix_chat_web.ex
  • examples/15-phoenix-chat-haxe-first/lib/phoenix_chat_web/components/**

Why this split exists: Phoenix project/config conventions are already Elixir-native and stable, while app behavior and framework modules can be type-checked and authored in Haxe.

Key Haxe snippets

Application (@:application):

@:application
@:appName("PhoenixChat")
class PhoenixChat {
  public static function start(type: ApplicationStartType, args: ApplicationArgs): ApplicationResult {
    var children:Array<ChildSpecFormat> = [
      TypeSafeChildSpec.telemetry(Telemetry),
      TypeSafeChildSpec.moduleWithConfig(DNSCluster, [{key: "query", value: dnsClusterQuery}]),
      TypeSafeChildSpec.pubSub(PubSub),
      TypeSafeChildSpec.moduleRef(ChatPresence),
      TypeSafeChildSpec.endpoint(Endpoint)
    ];
    return SupervisorExtern.startLink(children, options);
  }
}

Why this shape:

• catches unresolved module refs at compile time
• keeps supervision-tree code compact and explicit
• preserves standard OTP child-spec runtime output

For pure Elixir modules, this example adds small extern wrappers under src_haxe/phoenix_chat_hx/infrastructure/ (for example @:native("PhoenixChat.PubSub") @:unsafeExtern extern class PubSub {}) so callsites stay typed.

Router (@:router module-level field):

import reflaxe.elixir.macros.RouterDsl.*;

@:native("PhoenixChatWeb.Router")
@:router
final routes = [
  pipeline(browser, [
    plug(accepts, {initArgs: ["html"]}),
    plug(fetch_session),
    plug(fetch_live_flash),
    plug(protect_from_forgery),
    plug(put_secure_browser_headers)
  ]),
  scope("/", [
    pipeThrough([browser]),
    liveSession("default", [live("/", AppLive)])
  ])
];

Note: live routes can omit actions (live("/", AppLive)), which keeps LiveView modules free of placeholder index/show/edit methods when you do not need route-action dispatch.

Build configuration

• examples/15-phoenix-chat-haxe-first/build.hxml
  • -D elixir_output=lib so Haxe-generated server modules land in standard Phoenix lib/** paths.
  • Includes app + router + live/presence modules in the compile roots.

Related docs

• Haxe-first walkthrough: docs/06-guides/PHOENIX_CHAT_TUTORIAL_HAXE_FIRST.md
• Hybrid walkthrough: docs/06-guides/PHOENIX_CHAT_TUTORIAL.md
• New app setup: docs/06-guides/PHOENIX_NEW_APP.md
• Type-safe child specs: docs/04-api-reference/TYPE_SAFE_CHILD_SPEC.md