import type { Constructor } from './function';
import type { Key, InferArrayType, Arr, TT$ } from './types';
export declare function chain<T>(exp: () => T, defaultValue?: T): T;
export declare function isErrorOf(e: any, errorCtor: Constructor): boolean;
export declare function ensureArray<T>(v: T): T extends Arr<any, 'readonly'> ? T : T[];
export declare function ensurePromise<T>(v: T | Promise<T>): Promise<T>;
export declare function ensureFunction<T>(v: T): T extends (...args: any[]) => any ? T : never;
declare type Filler<T> = (i: number) => T;
export declare const arrayN: <T = any>(n: number, fill?: T | Filler<T>) => T[];
export declare const filterByKey: <A extends any[] | readonly any[], T extends InferArrayType<A>, V extends T[K], K extends Key = "type">(array: A, value: V, key?: K) => T extends { [k in K]: V; } ? T[] : never;
export declare const firstTruthy: <T>(...array: T[]) => any;
export declare const arrayFromIterable: <T>(it: Iterable<T>) => T[];
export interface PollOptions {
    duration: number;
    timeStep?: number;
}
export declare const poll: <S, E>(handler: () => TT$<{
    stop: boolean;
    error?: E;
    success?: S;
}>, options: PollOptions) => Promise<S>;
export {};