import * as Tp from "../../Collections/Immutable/Tuple";
import * as T from "../_internal/effect";
import * as GB from "../GroupBy";
import type { Stream } from "./definitions";
/**
 * More powerful version of `Stream.groupByKey`
 */
export declare function groupBy_<R, R1, E, E1, O, K, V>(self: Stream<R, E, O>, f: (o: O) => T.Effect<R1, E1, Tp.Tuple<[K, V]>>, buffer?: number): GB.GroupBy<R & R1, E | E1, K, V>;
/**
 * More powerful version of `Stream.groupByKey`
 */
export declare function groupBy<R1, E1, O, K, V>(f: (o: O) => T.Effect<R1, E1, Tp.Tuple<[K, V]>>, buffer?: number): <R, E>(self: Stream<R, E, O>) => GB.GroupBy<R & R1, E | E1, K, V>;
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