import { Effect, Signal } from './types.js';
/**
 * Run multiple signal writes as a single atomic update.
 * All effects and renders triggered inside fn() are deferred until the batch
 * completes, so each subscriber fires at most once.
 *
 * @example
 * batch(() => {
 *   setPrice(newPrice);    // ← would each trigger a render separately
 *   setVolume(newVolume);  // ← now both are coalesced into one render
 * });
 */
export declare function batch(fn: () => void): void;
export declare function setCurrentObserver(observer: Effect | null): void;
export declare function getCurrentObserver(): Effect | null;
export interface SignalOptions<T> {
    /**
     * Custom equality function. If it returns true the setter is a no-op and
     * no subscribers are notified.
     * Pass `false` to disable equality checks entirely (always notify).
     *
     * @default Object.is
     * @example
     * // Deep-equal arrays — only re-render when contents actually change
     * const [items, setItems] = signal([], { equals: (a, b) => JSON.stringify(a) === JSON.stringify(b) });
     *
     * // Always notify (useful for objects mutated in place)
     * const [state, setState] = signal(obj, { equals: false });
     */
    equals?: ((a: T, b: T) => boolean) | false;
}
/**
 * Fine-grained signal. Calling getter() inside a tracking context
 * auto-subscribes the observer to this signal.
 *
 * @example
 * const [count, setCount] = signal(0);
 * setCount(1);               // set directly
 * setCount(n => n + 1);      // updater function
 * console.log(count());      // 2
 */
export declare function signal<T>(initialValue: T, options?: SignalOptions<T>): Signal<T>;
/**
 * Derived signal. Lazily re-computes when any tracked dependency changes.
 * Reading computed() inside a tracking context also subscribes the observer
 * to this computed's upstream dependencies.
 *
 * @example
 * const [first, setFirst] = signal('Ada');
 * const [last,  setLast]  = signal('Lovelace');
 * const full = computed(() => `${first()} ${last()}`);
 * console.log(full()); // 'Ada Lovelace'
 * setFirst('Grace');
 * console.log(full()); // 'Grace Lovelace'
 */
export declare function computed<T>(fn: () => T): () => T;