export declare function isFunction<T extends (...args: any[]) => any>(val: unknown): val is T;
export declare const isUndefined: (val: any) => val is undefined;
export declare const isNumber: (val: any) => val is number;
export declare const isString: (val: any) => val is string;
export declare function isDate(val: Date): boolean;
export declare function isBoolean(val: unknown): val is boolean;
/**
 * 过滤出非undefined | null | '' 的集合
 * @param {any[]} val 数据源
 * @returns {any[]} 过滤后数据
 */
type NotFalsy<T> = T extends "" | null | undefined ? never : T;
export declare function normalizeValue<T>(val: T[]): NotFalsy<T>[];
export declare function isNil(val: any): boolean;
/**
 * Object.is
 * @param value
 * @param diffValue
 */
export declare function isEqual(value: any, diffValue: any): boolean;
export {};