Step 1 - One value

Future<int> once() async => 1;

Future<void> main() async {
  print(await once());
}

Step 2 - Many values

Stream<int> countTo(int n) async* {
  for (var i = 1; i <= n; i++) {
    yield i;
  }
}

Future<void> main() async {
  await for (final v in countTo(3)) {
    print(v);
  }
}

Step 3 - Mental model

• Future<T> completes once with T or an error.
• Stream<T> emits T events, then may close, or may signal an error.

Good habit

• If callers need partial results or cancellations, lean toward Stream or pass a callback; if there is exactly one outcome, prefer Future.

Practice tasks

• Rewrite countTo using Stream.periodic and take instead of async*.
• Name one browser or CLI event that is naturally a stream (keyboard, ticks, socket chunks).