State

An entity that manages transitioning and exposing state to view's.

Type Signature

state Counter($value = 0) -> {
  mut increment -> $value++;
  mut decrement -> $value--;
}

Constructing state containers

Parameters provided to state containers witho no default values must be provided to use the state in a provider.

state Counter(value: number) -> { }

Exposing constructor values

The value of value will be made available as $value or on the alias directly as value.

state Counter($value: number) -> { }

Default constructor values

Constructor arguments can have default values provided.

state Counter(value = 0) -> { }

Mutate state values

Modify the values in your state purely with mutators.

state StateWithMutator -> {
  value = 0;

  mut add(addend: number) -> $value += addend;
}

Private state values

Simplify the interface of your state container by hiding internal values.

state PrivateState -> {
  private quarters: number;
  private dimes: number;
  private nickels: number;
}

Getters to override or expose values

state StateWithGetter -> {
  private quarters: number;
  private dimes: number;
  private nickels: number;

  get total(pennies: number) -> $quarters * 25 + $dimes * 10 + $nickels * 5 + pennies;
}

Omit Parentheses

When your signature or getter or mutator does not accept parameters, the parentheses can be omitted.

// not preferred
state SimpleState() -> {
  get total() -> /* ... */;

  mut increment() -> /* ... */;
}

// preferred
state SimpleState -> {
  get total -> /* ... */;

  mut increment -> /* ... */;
}