import type { Maybe } from "../functional/maybe";
import type { MaybePromise } from "../functional/maybe_promise";
/** Host hooks for the shared async-chain update algorithm. */
export interface UpdateChain<T> {
    getCurrent(): T;
    setCurrent(value: T): void;
    getPending(): Maybe<Promise<T>>;
    setPending(p: Maybe<Promise<T>>): void;
    notify(): void;
}
/**
 * Shared `update()` logic for State and Store.
 *
 * Async updates chain: a second update issued while a previous async update is
 * still in flight runs against the previous update's result, not against the
 * snapshot at issue time. `set` clears `pending` to cancel any in-flight links.
 *
 * If a link rejects, the chain is unwedged — when the rejected link is still
 * the tail, `pending` is cleared so the next `update()` starts a fresh chain
 * instead of chaining off a rejected promise (which would never commit again).
 * The error is re-thrown so it surfaces rather than being silently swallowed.
 */
export declare function chainUpdate<T>(host: UpdateChain<T>, fn: (current: T) => MaybePromise<T>): void;