Scheduling Streams
When working with streams, you might need to introduce specific time intervals between each emission of stream elements. This can be achieved using the Stream.schedule combinator.
1import { import StreamStream, import ScheduleSchedule, import ConsoleConsole, import EffectEffect } from "effect"2
3const const stream: Stream.Stream<number, never, never>stream = import StreamStream.const make: <[number, number, number, number, number]>(as_0: number, as_1: number, as_2: number, as_3: number, as_4: number) => Stream.Stream<number, never, never>Creates a stream from an sequence of values.
make(1, 2, 3, 4, 5).(method) Pipeable.pipe<Stream.Stream<number, never, never>, Stream.Stream<number, never, never>, Stream.Stream<number, never, never>>(this: Stream.Stream<...>, ab: (_: Stream.Stream<number, never, never>) => Stream.Stream<...>, bc: (_: Stream.Stream<...>) => Stream.Stream<...>): Stream.Stream<...> (+21 overloads)pipe(4 import StreamStream.const schedule: <number, number, never, number>(schedule: Schedule.Schedule<number, number, never>) => <E, R>(self: Stream.Stream<number, E, R>) => Stream.Stream<number, E, R> (+1 overload)Schedules the output of the stream using the provided `schedule`.
schedule(import ScheduleSchedule.const spaced: (duration: DurationInput) => Schedule.Schedule<number>Returns a schedule that recurs continuously, each repetition spaced the
specified duration from the last run.
spaced("1 second")),5 import StreamStream.const tap: <number, void, never, never>(f: (a: number) => Effect.Effect<void, never, never>) => <E, R>(self: Stream.Stream<number, E, R>) => Stream.Stream<number, E, R> (+1 overload)Adds an effect to consumption of every element of the stream.
tap(import ConsoleConsole.const log: (...args: ReadonlyArray<any>) => Effect.Effect<void>log)6)7
8import EffectEffect.const runPromise: <Chunk<number>, never>(effect: Effect.Effect<Chunk<number>, never, never>, options?: {
readonly signal?: AbortSignal;
} | undefined) => Promise<Chunk<number>>Executes an effect and returns a `Promise` that resolves with the result.
Use `runPromise` when working with asynchronous effects and you need to integrate with code that uses Promises.
If the effect fails, the returned Promise will be rejected with the error.
runPromise(import StreamStream.const runCollect: <number, never, never>(self: Stream.Stream<number, never, never>) => Effect.Effect<Chunk<number>, never, never>Runs the stream and collects all of its elements to a chunk.
runCollect(const stream: Stream.Stream<number, never, never>stream)).(method) Promise<Chunk<number>>.then<void, never>(onfulfilled?: ((value: Chunk<number>) => void | PromiseLike<void>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<...>Attaches callbacks for the resolution and/or rejection of the Promise.
then(namespace console
var console: ConsoleThe `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
The module exports two specific components:
* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v22.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v22.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.
_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v22.x/api/process.html#a-note-on-process-io) for
more information.
Example using the global `console`:
```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
// Error: Whoops, something bad happened
// at [eval]:5:15
// at Script.runInThisContext (node:vm:132:18)
// at Object.runInThisContext (node:vm:309:38)
// at node:internal/process/execution:77:19
// at [eval]-wrapper:6:22
// at evalScript (node:internal/process/execution:76:60)
// at node:internal/main/eval_string:23:3
const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```
Example using the `Console` class:
```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);
myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err
const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
console.(method) globalThis.Console.log(message?: any, ...optionalParams: any[]): voidPrints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v22.x/api/util.html#utilformatformat-args)).
```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```
See [`util.format()`](https://nodejs.org/docs/latest-v22.x/api/util.html#utilformatformat-args) for more information.
log)9/*10Output:11112213314415516{17 _id: "Chunk",18 values: [ 1, 2, 3, 4, 5 ]19}20*/In this example, we’ve used the Schedule.spaced("1 second") schedule to introduce a one-second gap between each emission in the stream.