import type { Class } from './util';
/**
 * returns true if val is array, it won't check items of array
 */
export declare function isArray<T = any>(val?: unknown): val is Array<T>;
/**
 * returns true if val is function
 */
export declare function isFunction<T extends Function>(val?: unknown): val is T;
/**
 * returns true if val is generator function
 */
export declare function isGeneratorFunction(val?: unknown): val is GeneratorFunction;
/**
 * returns true if val is async function
 */
export declare function isAsyncFunction(val?: unknown): val is Function;
/**
 * returns true if val is async generator function
 */
export declare function isAsyncGeneratorFunction(val?: unknown): val is AsyncGeneratorFunction;
/**
 * returns true if val is object
 */
export declare function isObject(val?: unknown): val is object;
/**
 * returns true if val is class
 * *Note:* "class" is supported in ECMAScript 6, and if the code is using some compiler or transpiler, the checking might fail
 */
export declare function isClass<T extends Class>(val?: unknown): val is T;
/**
 * returns true if val is regular expression
 */
export declare function isRegExp(val?: unknown): val is RegExp;
/**
 * returns true if val is instance of Date
 */
export declare function isDate(val?: unknown): val is Date;
/**
 * returns true if val is instance of Error
 */
export declare function isError(val?: unknown): val is Error;
/**
 * returns true if val is generator
 */
export declare function isGenerator(val?: unknown): val is Generator;
/**
 * returns true if val is promise
 */
export declare function isPromise<T = any>(val?: unknown): val is Promise<T>;
/**
 * returns true if val is like promise, if the object has `then` property, the checking will pass.
 */
export declare function isPromiseLike<T = any>(val?: unknown): val is PromiseLike<T>;