export type NextStateGetter<T> = T | ((prev: T) => T);
export interface IObservable<T> {
    get: () => T;
    onUpdate: (fn: (state: T) => void) => () => void;
    update: (getNextState: T | ((prev: T) => T)) => void;
}
export declare class Observable<T> implements IObservable<T> {
    private _state;
    private pubsy;
    constructor(_state: T);
    get(): T;
    onUpdate(fn: (state: T) => void): () => void;
    update(nextStateGetter: NextStateGetter<T>): this;
    /**
     * Ability to transform the state
     *
     * @param mapFn
     * @returns
     */
    map<T1>(mapFn: (state: T) => T1): Observable<T1>;
    static getNextStateFrom: <T_1>(prev: T_1, a: NextStateGetter<T_1>) => T_1;
}