@effect-ts/system/_src/Experimental/Stream/_internal/api/groupByKey.ts

Effect-TS is a zero dependency set of libraries to write highly productive, purely functional TypeScript at scale.

// ets_tracing: off

import * as Tp from "../../../../Collections/Immutable/Tuple/index.js"
import * as T from "../../../../Effect/index.js"
import type * as GB from "../../GroupBy/index.js"
import type * as C from "../core.js"
import * as GroupBy from "./groupBy.js"

/**
 * Partition a stream using a function and process each stream individually.
 * This returns a data structure that can be used
 * to further filter down which groups shall be processed.
 *
 * After calling apply on the GroupBy object, the remaining groups will be processed
 * in parallel and the resulting streams merged in a nondeterministic fashion.
 *
 * Up to `buffer` elements may be buffered in any group stream before the producer
 * is backpressured. Take care to consume from all streams in order
 * to prevent deadlocks.

 */
export function groupByKey_<R, E, A, K>(
  self: C.Stream<R, E, A>,
  f: (a: A) => K,
  buffer = 16
): GB.GroupBy<R, E, K, A, A> {
  return GroupBy.groupBy_(self, (a) => T.succeed(Tp.tuple(f(a), a)), buffer)
}

/**
 * Partition a stream using a function and process each stream individually.
 * This returns a data structure that can be used
 * to further filter down which groups shall be processed.
 *
 * After calling apply on the GroupBy object, the remaining groups will be processed
 * in parallel and the resulting streams merged in a nondeterministic fashion.
 *
 * Up to `buffer` elements may be buffered in any group stream before the producer
 * is backpressured. Take care to consume from all streams in order
 * to prevent deadlocks.
 *
 * @ets_data_first groupByKey_
 */
export function groupByKey<A, K>(f: (a: A) => K, buffer = 16) {
  return <R, E>(self: C.Stream<R, E, A>) => groupByKey_(self, f, buffer)
}