<A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<
A,
Pull.ExcludeDone<E>,
R
>Creates a stream by repeatedly running an effect that yields an iterable of values.
Example (Repeating an iterable effect)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.fromIterableEffectRepeat(Effect.succeed([1, 2])).pipe(
Stream.take(5)
)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2, 1, 2, 1 ]constructors
Source effect/Stream.ts:11783 lines
export const const fromIterableEffectRepeat: <A, E, R>(
iterable: Effect.Effect<Iterable<A>, E, R>
) => Stream<A, Pull.ExcludeDone<E>, R>
Creates a stream by repeatedly running an effect that yields an iterable of values.
Example (Repeating an iterable effect)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.fromIterableEffectRepeat(Effect.succeed([1, 2])).pipe(
Stream.take(5)
)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2, 1, 2, 1 ]
fromIterableEffectRepeat = <function (type parameter) A in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>A, function (type parameter) E in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>E, function (type parameter) R in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>R>(
iterable: Effect.Effect<Iterable<A>, E, R>(parameter) iterable: {
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; <…;
toString: () => string;
toJSON: () => unknown;
}
import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<import IterableIterable<function (type parameter) A in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>A>, function (type parameter) E in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>E, function (type parameter) R in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>R>
): 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, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>A, import PullPull.type Pull.ExcludeDone = /*unresolved*/ anyExcludeDone<function (type parameter) E in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>E>, function (type parameter) R in <A, E, R>(iterable: Effect.Effect<Iterable<A>, E, R>): Stream<A, Pull.ExcludeDone<E>, R>R> => const flatMap: {
<A, A2, E2, R2>(
f: (a: A) => Stream<A2, E2, R2>,
options?:
| {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly bufferSize?: number | undefined
}
| undefined
): <E, R>(
self: Stream<A, E, R>
) => Stream<A2, E2 | E, R2 | R>
<A, E, R, A2, E2, R2>(
self: Stream<A, E, R>,
f: (a: A) => Stream<A2, E2, R2>,
options?:
| {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly bufferSize?: number | undefined
}
| undefined
): Stream<A2, E | E2, R | R2>
}
const fromEffectRepeat: <A, E, R>(
effect: Effect.Effect<A, E, R>
) => Stream<A, Pull.ExcludeDone<E>, R>
Creates a stream from an effect producing a value of type A which repeats forever.
Example (Repeating an effect forever)
import { Console, Effect, Random, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.fromEffectRepeat(Random.nextInt).pipe(
Stream.take(5)
)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 3891571149, 4239494205, 2352981603, 2339111046, 1488052210 ]
fromEffectRepeat(iterable: Effect.Effect<Iterable<A>, E, R>(parameter) iterable: {
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; <…;
toString: () => string;
toJSON: () => unknown;
}
const fromIterable: <A>(
iterable: Iterable<A>,
options?: {
readonly chunkSize?: number | undefined
}
) => Stream<A>
Creates a new Stream from an iterable collection of values.
Details
chunkSize: Maximum number of values emitted per chunk.
Example (Creating a stream from an iterable)
import { Console, Effect, Stream } from "effect"
const numbers = [1, 2, 3]
const program = Effect.gen(function*() {
const stream = Stream.fromIterable(numbers)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2, 3 ]
fromIterable)