type EmptyFn<V> = () => V;
type PresentFn<P, V> = (value: P) => V;
export declare abstract class Optional<T> {
    readonly value?: T | undefined;
    protected constructor(value?: T | undefined);
    abstract isPresent(): boolean;
    abstract isEmpty(): boolean;
    abstract get(): T;
    present<V = unknown>(callback: (value: T) => V): Undefined<V>;
    empty<V = unknown>(callback: () => V): Undefined<V>;
    when<V = unknown>(present: PresentFn<T, V>, empty: EmptyFn<V>): V;
    static build<T>(value?: Nulleable<T>): Optional<T>;
    static of<T>(value: T): Optional<T>;
    static empty<T>(): Optional<T>;
}
export {};