Pocak

State machine

States:

// enum
const Turnstil = {
  0: "Locked",
  1: "Unlocked",
  Locked: 0,
  Unlocked: 1
};

Inputs or actions that are taken to change the state:

const coin = (current, states) => () => {
  if (current === states.Locked) {
    return states.Unlocked;
  }
  return current;
};

const push = (current, states) => () => {
  if (current === states.Unlocked) {
    return states.Locked;
  }
  return current;
};

To create a state machine you can use enums or arrays.

const [state, coin, push] = stateMachine(Turnstil, [coin, push]);

// OR

const [state, coin, push] = stateMachine(["Locked", "Unlocked"], [coin, push]);

// default state is the first enum or the first element in the array

state(); // => Locked

coin();

state(); // => Unlocked

push();

state(); // => Locked

Subscription to state changes is also possible:

state.subscribe((current, next) =>
  console.log(`state transition from ${current} to ${next}`)
);