import { either as E } from 'fp-ts';
/**
 * @param color - color in any format acceptable by the `toRGB` function.
 * @returns True if the color is recognized as dark.
 * @see toRGB
 */
export declare function isColorDarkFp(color: string): E.Either<Error, boolean>;
/**
 * @see isColorDarkFp
 */
export declare const isColorDark: ((color: string) => boolean) & {};