export interface Rule {
    readonly error?: string | string[];
    readonly label?: string;
}
export declare function errors(loose: Rule): string[];
export declare function rule(test: () => string | string[] | undefined): Rule;
export declare type ErrorFormat = (label: string, error: string) => string;
export declare function label(label: string, error: string): string;
export declare function rules(rules: Rule[], optionalFormat?: ErrorFormat): Rule;
export declare function props(rule: Rule, props: {
    className?: string;
    errorClass?: string;
    title?: string;
}): {
    className: string | undefined;
    title: string | undefined;
};