Computed State

import { createStore, computed, computedFrom } from '@sinuxjs/core';

const store = createStore({ firstName: 'John', lastName: 'Doe' }, {
  setFirst: (s, name: string) => ({ firstName: name }),
});

const fullName = computed(store, s => `${s.firstName} ${s.lastName}`);
fullName.get(); // 'John Doe'
fullName.subscribe(() => console.log(fullName.get()));

computed(store, deriveFn) creates a derived value that auto-updates.

• Only recomputes when deriveFn returns a new value (Object.is check)
• computedFrom([store1, store2], (...states) => result) for multi-store derivation
• Both return { get(), subscribe(cb) } -- compatible with useSyncExternalStore

In React

import { useComputed } from '@sinuxjs/react';
const name = useComputed(fullName);

See also: useComputed.