Signals (Advanced)

Recommended API

For most application development, we recommend using the unified state() API. The low-level signal and computed primitives have been unified into state().

The signal Primitive

A SignalNode is the atomic unit of reactivity. It holds a value and notifies subscribers when it changes.

import { state } from 'flexium/core'

// Create
const count = state(0)

// Read (tracks dependency)
console.log(count.valueOf())

// Write (triggers notifications)
count.set(5)
// OR
count.set(c => c + 1)

Methods

• count.valueOf(): Getter. Accessing it tracks the signal in the current effect.
• count.peek(): Reads the value without tracking.
• count.set(val): Sets the value.

The computed Primitive

Derived values that automatically update when their dependencies change.

import { state } from 'flexium/core'

const count = state(1)
const double = state(() => count.valueOf() * 2)

console.log(double.valueOf()) // 2

count.set(5)
console.log(double.valueOf()) // 10

• Lazy: Computeds are only re-evaluated when read.
• Cached: If dependencies haven't changed, the cached value is returned.
• Pure: Computed functions should be pure and side-effect free.

Comparison with state()

Feature	state()
Import	flexium/core
Interface	Proxy
Ergonomics	Concise
JSX	Supported ({count})

Manual Subscriptions

If you need to manually listen to a signal outside of an effect (e.g. bridging to another library):

import { effect, state } from 'flexium/core'

const count = state(0)

const dispose = effect(() => {
  console.log('Stream updated:', count.valueOf())
})

// later
dispose()