Hyperlinkv0.8.0-beta.28

← Channel

Channel.switchMapconsteffect/Channel.ts:5816
<OutElem, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(
  f: (
    d: OutElem
  ) => Channel<
    OutElem1,
    OutErr1,
    OutDone1,
    InElem1,
    InErr1,
    InDone1,
    Env1
  >,
  options?: {
    readonly concurrency?: number | "unbounded" | undefined
    readonly bufferSize?: number | undefined
  }
): <OutErr, OutDone, InElem, InErr, InDone, Env>(
  self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>
) => Channel<
  OutElem1,
  OutErr1 | OutErr,
  OutDone,
  InElem & InElem1,
  InErr & InErr1,
  InDone & InDone1,
  Env1 | Env
>
<
  OutElem,
  OutErr,
  OutDone,
  InElem,
  InErr,
  InDone,
  Env,
  OutElem1,
  OutErr1,
  OutDone1,
  InElem1,
  InErr1,
  InDone1,
  Env1
>(
  self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
  f: (
    d: OutElem
  ) => Channel<
    OutElem1,
    OutErr1,
    OutDone1,
    InElem1,
    InErr1,
    InDone1,
    Env1
  >,
  options?: {
    readonly concurrency?: number | "unbounded" | undefined
    readonly bufferSize?: number | undefined
  }
): Channel<
  OutElem1,
  OutErr | OutErr1,
  OutDone,
  InElem & InElem1,
  InErr & InErr1,
  InDone & InDone1,
  Env | Env1
>

Maps each output element to a channel and emits values from the most recent active child channels.

Details

With the default concurrency of 1, starting a new child channel interrupts the previous child channel. Use options.concurrency to allow more active child channels. The source channel's done value is preserved.

Example (Switching mapped channels)

import { Channel, Data } from "effect"

class SwitchError extends Data.TaggedError("SwitchError")<{
  readonly reason: string
}> {}

// Create a channel that outputs numbers
const numberChannel = Channel.fromIterable([1, 2, 3])

// Switch to new channels based on each value
const switchedChannel = Channel.switchMap(
  numberChannel,
  (n) => Channel.fromIterable([`value-${n}`])
)

// Outputs: "value-1", "value-2", "value-3"
sequencing
Source effect/Channel.ts:581691 lines
export const switchMap: {
  <OutElem, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(
    f: (d: OutElem) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>,
    options?: {
      readonly concurrency?: number | "unbounded" | undefined
      readonly bufferSize?: number | undefined
    }
  ): <OutErr, OutDone, InElem, InErr, InDone, Env>(
    self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>
  ) => Channel<
    OutElem1,
    OutErr1 | OutErr,
    OutDone,
    InElem & InElem1,
    InErr & InErr1,
    InDone & InDone1,
    Env1 | Env
  >
  <
    OutElem,
    OutErr,
    OutDone,
    InElem,
    InErr,
    InDone,
    Env,
    OutElem1,
    OutErr1,
    OutDone1,
    InElem1,
    InErr1,
    InDone1,
    Env1
  >(
    self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
    f: (d: OutElem) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>,
    options?: {
      readonly concurrency?: number | "unbounded" | undefined
      readonly bufferSize?: number | undefined
    }
  ): Channel<
    OutElem1,
    OutErr | OutErr1,
    OutDone,
    InElem & InElem1,
    InErr & InErr1,
    InDone & InDone1,
    Env | Env1
  >
} = dual(
  (args) => isChannel(args[0]),
  <
    OutElem,
    OutErr,
    OutDone,
    InElem,
    InErr,
    InDone,
    Env,
    OutElem1,
    OutErr1,
    OutDone1,
    InElem1,
    InErr1,
    InDone1,
    Env1
  >(
    self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
    f: (d: OutElem) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>,
    options?: {
      readonly concurrency?: number | "unbounded" | undefined
      readonly bufferSize?: number | undefined
    }
  ): Channel<
    OutElem1,
    OutErr | OutErr1,
    OutDone,
    InElem & InElem1,
    InErr & InErr1,
    InDone & InDone1,
    Env | Env1
  > =>
    self.pipe(
      map(f),
      mergeAll({
        ...options,
        concurrency: options?.concurrency ?? 1,
        switch: true
      })
    )
)
Referenced by 1 symbols
Stream.switchMap