Faisceau

Faisceau is a tiny opinionated wrapper around alien-signals that exposes class-based helpers for signals and computed values. It keeps the ergonomics of alien-signals while providing:

• Signal and Computed classes with get, peek, and set helpers.
• Type guards (isSignal, isComputed) for narrowing.
• A safe peek helper implemented via setActiveSub so side reads do not create subscriptions.
• A simple batch helper that pairs startBatch/endBatch.
• Full re-export of the underlying alien-signals API so you do not lose low-level access.

Installation

pnpm add faisceau

Quick start

import { batch, computed, effect, signal } from 'faisceau'

const count = signal(0)
const double = computed(() => count.get() * 2)
const status = signal<'idle' | 'dirty'>('idle')

effect(() => {
  console.log(
    'count is',
    count.get(),
    'double is',
    double.get(),
    'status is',
    status.peek() // peek avoids subscribing the effect to status changes
  )
})

count.set(1)
console.log(double.get()) // 2

// Update several signals in one go without retriggering the effect for `status`
batch(() => {
  status.set('dirty')
  count.set(count.get() + 1)
  status.set('idle')
})

Because Faisceau re-exports everything from alien-signals, you can still import granular primitives when you need them:

import { effect, effectScope, endBatch, setActiveSub, startBatch } from 'faisceau'

API

signal<T>(initialValue: T): Signal<T>

Creates a Signal instance backed by alien-signals.

• get() returns the current value and tracks.
• peek() returns the current value without tracking (temporarily clears the active subscriber).
• set(value: T) updates the value.

computed<T>(getter: (previousValue?: T) => T): Computed<T>

Creates a Computed instance backed by alien-signals.

• get() returns the derived value and tracks dependencies.
• peek() reads the current value without tracking.

isSignal(obj): obj is Signal<any> / isComputed(obj): obj is Computed<any>

Runtime guards that let TypeScript narrow when working with mixed values.

batch(fn: () => void)

Runs fn between startBatch and endBatch, letting alien-signals flush subscribers once.

License

MIT