@pyreon/machine

Reactive state machines for Pyreon. A machine is a constrained signal — it can only hold specific values and transition between them via specific events. Type-safe states and events inferred from the definition.

Install

bun add @pyreon/machine

Quick Start

import { createMachine } from '@pyreon/machine'

const machine = createMachine({
  initial: 'idle',
  states: {
    idle: { on: { FETCH: 'loading' } },
    loading: { on: { SUCCESS: 'done', ERROR: 'error' } },
    done: {},
    error: { on: { RETRY: 'loading' } },
  },
})

machine()              // 'idle' — reads like a signal
machine.send('FETCH')  // transition to 'loading'
machine.matches('loading') // true — reactive in effects/JSX

// Reactive in JSX
{() => machine.matches('loading') && <Spinner />}
{() => machine.matches('done') && <Results />}

Guards

Conditional transitions using guard functions:

const form = createMachine({
  initial: 'editing',
  states: {
    editing: {
      on: { SUBMIT: { target: 'submitting', guard: () => isValid() } },
    },
    submitting: { on: { SUCCESS: 'done', ERROR: 'editing' } },
    done: {},
  },
})

API

createMachine(config)

Create a reactive state machine. Config: initial (starting state) and states (state/event map).

Returns Machine:

| Property | Description | | --- | --- | | machine() | Read current state (reactive) | | send(event, payload?) | Trigger a transition | | matches(...states) | Check if in one of the given states (reactive) | | can(event) | Check if event would trigger a valid transition | | nextEvents() | Available events from current state | | reset() | Return to initial state | | onEnter(state, callback) | Fire callback when entering a state | | onTransition(callback) | Fire on any transition |

Use signals alongside machines for data. The machine manages transitions, signals manage data.

License

MIT