export declare class InMemoryRepository<T> {
    private readonly defaultFactory;
    private data;
    private readonly mutex;
    constructor(defaultFactory: () => T);
    read(): Promise<T>;
    write(next: T): Promise<void>;
    mutate<R>(fn: (cur: T) => {
        next: T;
        result: R;
    }): Promise<R>;
    /** No-op: there is no external state to invalidate. */
    invalidate(): void;
}