import type { AnyFunction } from './types/common.js';
export type CacheKeyFn<Fn extends AnyFunction, ReturnValue = unknown> = (args: Parameters<Fn>) => ReturnValue;
export type DefaultCacheKeyFn<Fn extends AnyFunction> = CacheKeyFn<Fn, NonNullable<Parameters<Fn>[0]> | string>;
export type MemoizedFn<Fn extends AnyFunction, CkFn extends CacheKeyFn<Fn>> = Fn & {
    cache: Map<ReturnType<CkFn>, ReturnType<Fn>>;
};
export declare function memo<Fn extends AnyFunction, CkFn extends CacheKeyFn<Fn>>(fn: Fn, getCacheKey: CkFn): MemoizedFn<Fn, CkFn>;
export declare function memo<Fn extends AnyFunction>(fn: Fn): MemoizedFn<Fn, DefaultCacheKeyFn<Fn>>;