interface Channel

The producer half of StreamClass.channel: emit into it, consume stream out of it.

const channel: Channel<string> = Stream.channel<string>();
channel.emit('a'); // true — buffered, room to spare
channel.buffered; // 1

Type Parameters

E = never

Properties

readonly
stream: Stream<T, E>

The consuming half. One consumer only; a second pass throws.

readonly
buffered: number

Elements buffered for a consumer that has not taken them yet.

readonly
dropped: number

How many elements the buffer has lost to overflow. 0 unless a consumer fell behind.

readonly
closed: boolean

Whether the channel has been closed, aborted, or abandoned by its consumer.

Methods

emit(value: T): boolean

Offers a value. Returns false when there is no room left — Node's write() convention: advisory for a producer that can slow down, ignorable for one that cannot.

fail(error: E): boolean

Offers a declared failure as an element — the railway, not a rejection.

close(): void

Ends the stream once the buffer drains. Idempotent.

abort(reason: unknown): void

Rejects the consuming Task with reason — the two-tier rule's bug tier. Idempotent.

ready(): Promise<void>

Resolves once there is room to emit again — Web Streams' writer.ready, and the promise form of Node's 'drain'.

Named for the condition it actually reports. It resolves when the buffer is below capacity, not when it is empty: with 9 of 10 buffered it resolves immediately, because there is room for a tenth. "Drained" would claim the opposite. It is also awaited in a loop rather than once, so it names a recurring gate, unlike the genuinely final closed.

Usage

import { type Channel } from "lib/stream/stream.ts";