<A, E>(pubsub: PubSub.PubSub<Take.Take<A, E>>): Stream<A, E>Creates a stream from a PubSub of Take values.
Details
Take values include end and failure signals.
Example (Creating a stream from PubSub takes)
import { Console, Effect, Exit, PubSub, Stream, Take } from "effect"
const program = Effect.gen(function*() {
const pubsub = yield* PubSub.unbounded<Take.Take<number, string>>({
replay: 3
})
yield* PubSub.publish(pubsub, [1])
yield* PubSub.publish(pubsub, [2])
yield* PubSub.publish(pubsub, Exit.succeed<void>(undefined))
const values = yield* Stream.fromPubSubTake(pubsub).pipe(Stream.runCollect)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2 ]export const const fromPubSubTake: <A, E>(
pubsub: PubSub.PubSub<Take.Take<A, E>>
) => Stream<A, E>
Creates a stream from a PubSub of Take values.
Details
Take values include end and failure signals.
Example (Creating a stream from PubSub takes)
import { Console, Effect, Exit, PubSub, Stream, Take } from "effect"
const program = Effect.gen(function*() {
const pubsub = yield* PubSub.unbounded<Take.Take<number, string>>({
replay: 3
})
yield* PubSub.publish(pubsub, [1])
yield* PubSub.publish(pubsub, [2])
yield* PubSub.publish(pubsub, Exit.succeed<void>(undefined))
const values = yield* Stream.fromPubSubTake(pubsub).pipe(Stream.runCollect)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2 ]
fromPubSubTake = <function (type parameter) A in <A, E>(pubsub: PubSub.PubSub<Take.Take<A, E>>): Stream<A, E>A, function (type parameter) E in <A, E>(pubsub: PubSub.PubSub<Take.Take<A, E>>): Stream<A, E>E>(pubsub: PubSub.PubSub<Take.Take<A, E>>(parameter) pubsub: {
pubsub: PubSub.Atomic<A>;
subscribers: PubSub.Subscribers<A>;
scope: Scope.Closeable;
shutdownHook: Latch.Latch;
shutdownFlag: MutableRef.MutableRef<boolean>;
strategy: PubSub.Strategy<A>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
import PubSubPubSub.interface PubSub<in out A>A PubSub<A> is an asynchronous message hub into which publishers can publish
messages of type A and subscribers can subscribe to take messages of type
A.
Example (Publishing and subscribing to messages)
import { Effect, PubSub } from "effect"
const program = Effect.gen(function*() {
// Create a bounded PubSub with capacity 10
const pubsub = yield* PubSub.bounded<string>(10)
// Subscribe and consume messages
yield* Effect.scoped(Effect.gen(function*() {
const subscription = yield* PubSub.subscribe(pubsub)
// Publish messages
yield* PubSub.publish(pubsub, "Hello")
yield* PubSub.publish(pubsub, "World")
const message1 = yield* PubSub.take(subscription)
const message2 = yield* PubSub.take(subscription)
console.log(message1, message2) // "Hello", "World"
}))
})
Companion namespace containing the low-level building blocks used by
PubSub, including atomic implementations, backing subscriptions, replay
windows, and delivery strategies.
PubSub<import TakeTake.type Take<A, E = never, Done = void> =
| readonly [A, ...A[]]
| Exit.Exit<Done, E>
Represents one pull result: either a non-empty batch of values, a failure
Exit, or a successful Exit that signals completion with a Done value.
When to use
Use to store, transfer, or interpret pull results later while preserving
emitted values, failures, and normal completion.
Take<function (type parameter) A in <A, E>(pubsub: PubSub.PubSub<Take.Take<A, E>>): Stream<A, E>A, function (type parameter) E in <A, E>(pubsub: PubSub.PubSub<Take.Take<A, E>>): Stream<A, E>E>>): interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E>(pubsub: PubSub.PubSub<Take.Take<A, E>>): Stream<A, E>A, function (type parameter) E in <A, E>(pubsub: PubSub.PubSub<Take.Take<A, E>>): Stream<A, E>E> =>
const fromChannel: <
Arr extends Arr.NonEmptyReadonlyArray<any>,
E,
R
>(
channel: Channel.Channel<
Arr,
E,
void,
unknown,
unknown,
unknown,
R
>
) => Stream<
Arr extends Arr.NonEmptyReadonlyArray<infer A>
? A
: never,
E,
R
>
Creates a stream from a array-emitting Channel.
Example (Creating a stream from an array-emitting channel)
import { Channel, Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const channel = Channel.succeed([1, 2, 3] as const)
const stream = Stream.fromChannel(channel)
const result = yield* Stream.runCollect(stream)
yield* Console.log(result)
})
// Output: [ 1, 2, 3 ]
fromChannel(import ChannelChannel.const fromPubSubTake: <A, E, Done>(
pubsub: PubSub.PubSub<Take.Take<A, E, Done>>
) => Channel<
Arr.NonEmptyReadonlyArray<A>,
E,
Done
>
Subscribes to a PubSub of Take values and exposes them as a channel.
Details
Output Take values are emitted as non-empty arrays. Failed Take values
fail the channel. Done Take values complete the channel.
fromPubSubTake(pubsub: PubSub.PubSub<Take.Take<A, E>>(parameter) pubsub: {
pubsub: PubSub.Atomic<A>;
subscribers: PubSub.Subscribers<A>;
scope: Scope.Closeable;
shutdownHook: Latch.Latch;
shutdownFlag: MutableRef.MutableRef<boolean>;
strategy: PubSub.Strategy<A>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}