declare const BoxSymbol: unique symbol;
declare const isWritableSymbol: unique symbol;
export type ReadableBox<T> = {
    readonly [BoxSymbol]: true;
    readonly current: T;
};
export type WritableBox<T> = {
    readonly [isWritableSymbol]: true;
    current: T;
};
export declare function isFunction(value: unknown): value is (...args: unknown[]) => unknown;
export declare function isObject(value: unknown): value is Record<PropertyKey, unknown>;
export declare function box<T>(): WritableBox<T | undefined>;
export declare function box<T>(initialValue: T): WritableBox<T>;
export {};