Hyperlinkv0.8.0-beta.28

← Stream

Stream.runFoldconsteffect/Stream.ts:10707
<Z, A>(initial: LazyArg<Z>, f: (acc: Z, a: A) => Z): <E, R>(
  self: Stream<A, E, R>
) => Effect.Effect<Z, E, R>
<A, E, R, Z>(
  self: Stream<A, E, R>,
  initial: LazyArg<Z>,
  f: (acc: Z, a: A) => Z
): Effect.Effect<Z, E, R>

Runs the stream and folds elements using a pure reducer.

Example (Folding stream values)

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

const program = Effect.gen(function*() {
  const total = yield* Stream.runFold(
    Stream.make(1, 2, 3),
    () => 0,
    (acc, n) => acc + n
  )
  yield* Console.log(total)
})

Effect.runPromise(program)
// 6
destructors
Source effect/Stream.ts:1070723 lines
export const runFold: {
  <Z, A>(
    initial: LazyArg<Z>,
    f: (acc: Z, a: A) => Z
  ): <E, R>(
    self: Stream<A, E, R>
  ) => Effect.Effect<Z, E, R>
  <A, E, R, Z>(
    self: Stream<A, E, R>,
    initial: LazyArg<Z>,
    f: (acc: Z, a: A) => Z
  ): Effect.Effect<Z, E, R>
} = dual(3, <A, E, R, Z>(
  self: Stream<A, E, R>,
  initial: LazyArg<Z>,
  f: (acc: Z, a: A) => Z
): Effect.Effect<Z, E, R> =>
  Channel.runFold(self.channel, initial, (acc, arr) => {
    for (let i = 0; i < arr.length; i++) {
      acc = f(acc, arr[i])
    }
    return acc
  }))