Variable Transition

Type Declaration

• InvalidTransition: typeof InvalidTransition

• make: <const C extends Record<string, readonly TransitionTarget<string & keyof C>[]>>(
      config: C,
      initial: string & keyof C,
  ) => Effect<Transition<string & keyof C>, never, Scope>

  Create a state machine with declarative transitions.

  Example: Basic usage

  const status = yield* Transition.make(
    {
      idle: ["loading"],
      loading: ["success", "error"],
      success: ["idle"],
      error: ["idle", "loading"],
    },
    "idle"
  );
  
  yield* status.to("loading"); // works
  yield* status.to("success"); // fails - not allowed from idle
  
  // Reactive checks
  status.is("idle");              // Readable<boolean>
  status.canTransitionTo("error"); // Readable<boolean>
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  Example: With guards

  const isOnline = yield* Signal.make(true);
  
  const status = yield* Transition.make(
    {
      idle: [{ to: "loading", when: isOnline }, "error"],
      loading: ["success", "error"],
      success: ["idle"],
      error: ["idle"],
    },
    "idle"
  );
  
  // canTransitionTo respects guards
  status.canTransitionTo("loading"); // true only when isOnline is true
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  Example: Guarded callbacks

  const submit = status.guard(
    ["idle"],
    (data: FormData) => submitForm(data),
    { onBlocked: "ignore" }
  );
  
  yield* submit(formData); // runs only if in "idle" state
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