npm:xactor | Skypack

README

_{The Actor Model for JavaScript}

🚧 Work in progress! 🚧

XActor is an actor model implementation for JavaScript and TypeScript, heavily inspired by Akka. It represents the "actor model" parts of XState and can be used with or without XState.

Resources

Learn more about the Actor Model:

Installation

With npm: npm install xactor --save
With Yarn: yarn add xactor

Quick Start

Simple Example:

import { createSystem, createBehavior } from 'xactor';

// Yes, I know, another trivial counter example
const counter = createBehavior(
  (state, message, context) => {
    if (message.type === 'add') {
      context.log(`adding ${message.value}`);

      return {
        ...state,
        count: state.count + message.value,
      };
    }

    return state;
  },
  { count: 0 }
);

const counterSystem = createSystem(counter, 'counter');

counterSystem.subscribe(state => {
  console.log(state);
});

counterSystem.send({ type: 'add', value: 3 });
// => [counter] adding 3
// => { count: 3 }
counterSystem.send({ type: 'add', value: 1 });
// => [counter] adding 1
// => { count: 4 }

API

`createBehavior(reducer, initialState)`

Creates a behavior that is represented by the reducer and starts at the initialState.

Arguments

reducer - a reducer that takes 3 arguments (state, message, actorContext) and should return the next state (tagged or not).
initialState - the initial state of the behavior.

Reducer Arguments

state - the current untagged state.
message - the current message to be processed by the reducer.
actorContext - the actor context of the actor instance using this behavior.

Actor Context

The actor context is an object that includes contextual information about the current actor instance:

self - the ActorRef reference to the own actor
system - the reference to the actor system that owns this actor
log - function for logging messages that reference the actor
spawn - function to spawn an actor
stop - function to stop a spawned actor
watch - function to watch an actor

Spawning Actors

Actors can be spawned via actorContext.spawn(behavior, name) within a behavior reducer:

const createTodo = (content = "") => createBehavior((state, msg, ctx) => {
  // ...
  
  return state;
}, { content });

const todos = createBehavior((state, msg, ctx) => {
  if (msg.type === 'todo.create') {
    return {
      ...state,
      todos: [
        ...state.todos,
        ctx.spawn(createTodo(), 'some-unique-todo-id')
      ]
    }
  }
  
  // ...
  
  return state;
}, { todos: [] });

const todoSystem = createSystem(todos, 'todos');

todoSystem.send({ type: 'todo.create' });

Documentation still a work-in-progress! Please see the tests for now as examples.