Futures, Streams & Async Errors

Futures, Streams & Async Errors requires clear event-loop responsiveness, Future and Stream errors, subscription lifecycles, and isolate message boundaries. Use async for I/O and Isolate.run for CPU-heavy work.

Build a Complete Mental Model

Futures, Streams & Async Errors requires clear event-loop responsiveness, Future and Stream errors, subscription lifecycles, and isolate message boundaries. Use async for I/O and Isolate.run for CPU-heavy work.

Apply It in Modern Dart

Run and test an original Futures, Streams & Async Errors example with null, empty, boundary, invalid, async-error, and cancellation cases. Use dart format, dart analyze, and dart test, and verify Future or Stream subscriptions and isolate boundaries where relevant.

After This Lesson

• Explain nullability, mutability, and async contracts
• Write an example that passes dart analyze
• Test a failure or async case

Stream<int> squares() async* {
  for (var value in [1, 2, 3]) {
    await Future<void>.delayed(Duration.zero);
    yield value * value;
  }
}

Future<void> main() async {
  await for (final value in squares()) {
    print(value);
  }
}

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Asynchronous programming: Streams — Dart