import type { Validator } from '../Validator.js';
export type ValidatorOptions<T> = {
    message: (params: {
        value: T;
    }) => string;
};
export type DefineValidatorOptions<T> = ValidatorOptions<T> & {
    validator: (value: T) => boolean;
};
export declare function defineValidator<T>(options: DefineValidatorOptions<T>): Validator<T | null | undefined>;