LiveView Integration

< Handler Stacks | Up: Recipes | Index | Durable Computation >

AsyncCoroutine bridges effectful computations into Phoenix LiveView, enabling pausable state machines, conversational flows, and long-running operations without GenServer boilerplate.

Pattern

1. Write the state machine as an effectful computation using Yield
2. Start it with AsyncCoroutine.run/2
3. Handle {AsyncCoroutine, tag, result} messages in handle_info
4. Resume with user input via AsyncCoroutine.run/3

Multi-step wizard

alias Skuld.AsyncCoroutine

defmodule MyApp.Wizard do
  use Skuld.Syntax

  defcomp run do
    name <- Yield.yield(:get_name)
    email <- Yield.yield(:get_email)
    {:ok, %{name: name, email: email}}
  end
end

LiveView:

def mount(_params, _session, socket) do
  {:ok, runner} = AsyncCoroutine.run(MyApp.Wizard.run(), tag: :wizard)
  {:ok, assign(socket, runner: runner, step: :name)}
end

def handle_info({AsyncCoroutine, :wizard, %ExternalSuspend{value: :get_name}}, socket) do
  {:noreply, assign(socket, step: :name)}
end

def handle_event("submit_name", %{"name" => name}, socket) do
  AsyncCoroutine.run(socket.assigns.runner, name)
  {:noreply, socket}
end

def handle_info({AsyncCoroutine, :wizard, %ExternalSuspend{value: :get_email}}, socket) do
  {:noreply, assign(socket, step: :email)}
end

def handle_info({AsyncCoroutine, :wizard, {:ok, user}}, socket) do
  {:noreply, assign(socket, user: user, step: :done)}
end

Cancellation

Cancel on mount or when the user navigates away:

def mount(_params, _session, socket) do
  if connected?(socket) do
    # Cancel any previous wizard
    if socket.assigns[:runner], do: AsyncCoroutine.cancel(socket.assigns.runner)
  end
  ...
end

With EffectLogger

Persist wizard state for resumption after disconnects:

wizard = MyApp.Wizard.run()
|> EffectLogger.with_logging()
|> Reader.with_handler(%{})

{:ok, runner} = AsyncCoroutine.run(wizard, tag: :wizard)
# Extract log from ExternalSuspend.data when yielded

< Handler Stacks | Up: Recipes | Index | Durable Computation >