import { AsyncIterableLike } from "../async-like";
export interface Retainer<T> extends Iterable<T> {
    has?(value: T): boolean;
    add(value: T): void;
}
export interface RetainerWithHas<T> extends Retainer<T> {
    has(value: T): boolean;
}
export interface AsyncRetainer<T> extends AsyncIterable<T> {
    has?(value: T): boolean | Promise<boolean>;
    add(value: T): void | Promise<void>;
}
export interface AsyncRetainerWithHas<T> extends AsyncRetainer<T> {
    has(value: T): boolean | Promise<boolean>;
}
export declare function arrayRetainer<T>(has?: (value: T, values: T[]) => boolean): Retainer<T>;
export declare function setRetainer<T>(): RetainerWithHas<T>;
export declare function retain<T>(iterable: Iterable<T>, retainer?: Retainer<T>): Iterable<T>;
export declare function asyncRetain<T>(iterable: AsyncIterableLike<T>, retainer?: Retainer<T> | AsyncRetainer<T>): AsyncIterable<T>;