/**
 * A validation function, it should return null if there is no error, or a string if there is an error
 */
export declare type ValidationFn = (value: unknown | unknown[]) => string | null;
/**
 * A single validation rule with the name of the rule and validation function
 */
export declare type ValidationRule = Record<string, ValidationFn>;
/**
 * Custom validation rules for Formula
 */
export declare type ValidationRules = Record<string, ValidationRule>;
/**
 * Custom validation messages for field errors
 */
export declare type CustomValidationMessages = Record<string, Record<string, string>>;