# Water Example

### Example

A simple example showing the life cycle of H2O.

```dart
import 'package:fsm2/fsm2.dart';

void main() async {
  final machine = StateMachine.create((g) => g
    ..initialState<Solid>()
    ..state<Solid>((b) => b..on<OnMelted, Liquid>(sideEffect: () => print('Melted')))
    ..state<Liquid>((b) => b
      ..onEnter((s, e) => print('Entering ${s.runtimeType} State'))
      ..onExit((s, e) => print('Exiting ${s.runtimeType} State'))
      ..on<OnFroze, Solid>(sideEffect: (e) => print('Frozen'))
      ..on<OnVaporized, Gas>(sideEffect: (e) => print('Vaporized')))
    ..state<Gas>((b) => b..on<OnCondensed, Liquid>(
        sideEffect: (e) => print('Condensed')))
    ..onTransition((t) => print(
        'Recieved Event ${t.eventType} in State ${t.fromState.runtimeType} transitioning to State ${t.toState.runtimeType}')));

  /// static analysis of the state machine.
  /// only do this during testing.
  await machine.analyse();
  
  /// export the statemachine to a dot file so we can visualise it.
  await machine.export('test/test.gv');

  print(await machine.isInState<Solid>()); // TRUE

  machine.applyEvent(OnMelted());
  print(await machine.isInState<Liquid>()); // TRUE

  machine.applyEvent(OnFroze());
  print(await machine.isInState<Solid>()); // TRUE
}

class Solid extends State {}

class Liquid extends State {}

class Gas extends State {}

class OnMelted extends Event {}

class OnFroze extends Event {}

class OnVaporized extends Event {}

class OnCondensed extends Event {}

```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://fsm2.onepub.dev/water-example.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.