@effect-ts/system/_src/Experimental/Stream/_internal/api/crossLeft.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 type * as C from "../core.js"
import * as Cross from "./cross.js"
import * as Map from "./map.js"

/**
 * Composes this stream with the specified stream to create a cartesian product of elements,
 * but keeps only elements from this stream.
 * The `that` stream would be run multiple times, for every element in the `this` stream.
 */
export function crossLeft_<R, R1, E, E1, A, A1>(
  self: C.Stream<R, E, A>,
  that: C.Stream<R1, E1, A1>
): C.Stream<R & R1, E | E1, A> {
  return Map.map_(Cross.cross_(self, that), Tp.get(0))
}

/**
 * Composes this stream with the specified stream to create a cartesian product of elements,
 * but keeps only elements from this stream.
 * The `that` stream would be run multiple times, for every element in the `this` stream.
 *
 * @ets_data_first crossLeft_
 */
export function crossLeft<R1, E1, A1>(that: C.Stream<R1, E1, A1>) {
  return <R, E, A>(self: C.Stream<R, E, A>) => crossLeft_(self, that)
}