Hyperlinkv0.8.0-beta.28

Stream

Stream.zipLeftconsteffect/Stream.ts:3724
<AR, ER, RR>(right: Stream<AR, ER, RR>): <AL, EL, RL>(
  left: Stream<AL, EL, RL>
) => Stream<AL, ER | EL, RR | RL>
<AL, EL, RL, AR, ER, RR>(
  left: Stream<AL, EL, RL>,
  right: Stream<AR, ER, RR>
): Stream<AL, EL | ER, RL | RR>

Zips this stream with another point-wise and keeps only the values from the left stream.

Details

The resulting stream ends when either side ends.

Example (Zipping streams while keeping left values)

import { Console, Effect, Stream } from "effect"

const stream1 = Stream.make(1, 2, 3, 4)
const stream2 = Stream.make("a", "b")

const program = Effect.gen(function*() {
  const result = yield* Stream.zipLeft(stream1, stream2).pipe(Stream.runCollect)
  yield* Console.log(result)
})

Effect.runPromise(program)
// Output: [1, 2]
zipping
Source effect/Stream.ts:372418 lines
export const zipLeft: {
  <AR, ER, RR>(right: Stream<AR, ER, RR>): <AL, EL, RL>(left: Stream<AL, EL, RL>) => Stream<AL, ER | EL, RR | RL>
  <AL, EL, RL, AR, ER, RR>(left: Stream<AL, EL, RL>, right: Stream<AR, ER, RR>): Stream<AL, EL | ER, RL | RR>
} = dual(
  2,
  <AL, EL, RL, AR, ER, RR>(
    left: Stream<AL, EL, RL>,
    right: Stream<AR, ER, RR>
  ): Stream<AL, EL | ER, RL | RR> =>
    zipWithArray(left, right, (leftArr, rightArr) => {
      const minLength = Math.min(leftArr.length, rightArr.length)
      const output = leftArr.slice(0, minLength) as Arr.NonEmptyArray<AL>
      const leftoverLeft = leftArr.slice(minLength)
      const leftoverRight = rightArr.slice(minLength)

      return [output, leftoverLeft, leftoverRight] as const
    })
)