computed()

Create a read-only signal that auto-updates when dependencies change.

Signature

function computed<T>(fn: () => T): ReadonlySignal<T>

Parameters

Param	Type	Description
fn	() => T	Computation function — reads other signals

Returns

ReadonlySignal<T> — same as Signal but read-only (no .set(), .update(), or .value =).

Examples

import { signal, computed } from "@whisq/core";

const count = signal(3);
const double = computed(() => count.value * 2);

double.value; // 6
count.value = 5;
double.value; // 10 — auto-updated

🐱 Whisker Tip

Computed values are lazy and cached — they don’t recompute until read, and reading twice without changes returns the cached value.

Related primitives

• signal() — the mutable primitive computed() reads from.
• effect() — side effects triggered by signal/computed changes.
• batch() — group writes so dependent computeds re-read only once.
• partition() — convenience helper that returns two computeds splitting an array signal by a predicate.