export declare type NonPromise = undefined | {
    then?: undefined;
};
export declare type DefaultType<F> = F | {
    (): F & NonPromise;
};
export declare type CheckFunction<F> = ((name: string, mixed: any) => Promise<F>);
export declare type CheckType<F> = CheckFunction<F> | Schema<F> | {
    (): F & NonPromise;
};
export declare const DateInstance: () => Date;
export declare const StringArray: () => string[];
export declare const NumberArray: () => number[];
export declare const BooleanArray: () => boolean[];
export declare const DateArray: () => Date[];
export declare const OptionalString: () => string | undefined;
export declare const OptionalNumber: () => number | undefined;
export declare const OptionalBoolean: () => boolean | undefined;
export declare const OptionalDate: () => Date | undefined;
export declare type CheckObject<F> = {
    default: DefaultType<F>;
    check: CheckType<F>;
};
export declare type Field<T> = CheckType<T> | CheckObject<T>;
export declare type Fields<T> = {
    [fieldName in keyof T]: Field<T[fieldName]>;
};
export interface Schema<T> {
    allowExtraFields?: boolean;
    check?: (name: string, target: T) => Promise<void>;
    fields: Fields<T>;
}