<A, A2, E2, R2>(
f: (a: A, i: number) => Effect.Effect<A2, E2, R2>,
options?:
| {
readonly concurrency?: number | "unbounded" | undefined
readonly unordered?: boolean | 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, i: number) => Effect.Effect<A2, E2, R2>,
options?:
| {
readonly concurrency?: number | "unbounded" | undefined
readonly unordered?: boolean | undefined
}
| undefined
): Stream<A2, E | E2, R | R2>Maps over elements of the stream with the specified effectful function.
When to use
Use when each stream element transformation needs an Effect, service dependency, failure channel, or configured concurrency.
Example (Effectfully mapping stream values)
import { Console, Effect, Stream } from "effect"
const stream = Stream.make(1, 2, 3)
const mappedStream = stream.pipe(
Stream.mapEffect((n) =>
Effect.gen(function*() {
yield* Console.log(`Processing: ${n}`)
return n * 2
})
)
)
const program = Effect.gen(function*() {
const result = yield* Stream.runCollect(mappedStream)
yield* Console.log(result)
})
Effect.runPromise(program)
// Output:
// Processing: 1
// Processing: 2
// Processing: 3
// [2, 4, 6]mapping
Source effect/Stream.ts:202030 lines
export const const mapEffect: {
<A, A2, E2, R2>(
f: (
a: A,
i: number
) => Effect.Effect<A2, E2, R2>,
options?:
| {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | 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,
i: number
) => Effect.Effect<A2, E2, R2>,
options?:
| {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | undefined
}
| undefined
): Stream<A2, E | E2, R | R2>
}
Maps over elements of the stream with the specified effectful function.
When to use
Use when each stream element transformation needs an Effect, service
dependency, failure channel, or configured concurrency.
Example (Effectfully mapping stream values)
import { Console, Effect, Stream } from "effect"
const stream = Stream.make(1, 2, 3)
const mappedStream = stream.pipe(
Stream.mapEffect((n) =>
Effect.gen(function*() {
yield* Console.log(`Processing: ${n}`)
return n * 2
})
)
)
const program = Effect.gen(function*() {
const result = yield* Stream.runCollect(mappedStream)
yield* Console.log(result)
})
Effect.runPromise(program)
// Output:
// Processing: 1
// Processing: 2
// Processing: 3
// [2, 4, 6]
mapEffect: {
<function (type parameter) A in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) A2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) E2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) R2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
f: (
a: A,
i: number
) => Effect.Effect<A2, E2, R2>
a: Aa: function (type parameter) A in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
i: numberi: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<function (type parameter) A2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) E2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) R2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | undefined
}
| undefined
concurrency?: number | "unbounded" | undefinedconcurrency?: number | "unbounded" | undefined
readonly unordered?: boolean | undefinedunordered?: boolean | undefined
} | undefined
): <function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A2, E2 | E, R2 | R>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<A2, E2 | E, R2 | R>R>(self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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; <…;
}
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, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A2, E2 | E, R2 | R>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<A2, E2 | E, R2 | 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) A2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) E2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A2, E2 | E, R2 | R>E, function (type parameter) R2 in <A, A2, E2, R2>(f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): <E, R>(self: Stream<A, E, R>) => Stream<A2, E2 | E, R2 | R>
function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<A2, E2 | E, R2 | R>R>
<function (type parameter) A in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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; <…;
}
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, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
f: (
a: A,
i: number
) => Effect.Effect<A2, E2, R2>
a: Aa: function (type parameter) A in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
i: numberi: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | undefined
}
| undefined
concurrency?: number | "unbounded" | undefinedconcurrency?: number | "unbounded" | undefined
readonly unordered?: boolean | undefinedunordered?: boolean | undefined
} | undefined
): 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) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
import dualdual((args: anyargs) => const isStream: (
u: unknown
) => u is Stream<unknown, unknown, unknown>
Checks whether a value is a Stream.
Example (Checking whether a value is a Stream)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.make(1, 2, 3)
const notStream = { data: [1, 2, 3] }
yield* Console.log(Stream.isStream(stream))
// true
yield* Console.log(Stream.isStream(notStream))
// false
})
Effect.runPromise(program)
isStream(args: anyargs[0]), <function (type parameter) A in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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; <…;
}
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, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
f: (
a: A,
i: number
) => Effect.Effect<A2, E2, R2>
a: Aa: function (type parameter) A in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
i: numberi: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | undefined
}
| undefined
concurrency?: number | "unbounded" | undefinedconcurrency?: number | "unbounded" | undefined
readonly unordered?: boolean | undefinedunordered?: boolean | undefined
} | undefined
): 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) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (a: A, i: number) => Effect.Effect<A2, E2, R2>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
readonly unordered?: boolean | undefined;
} | undefined): Stream<A2, E | E2, R | R2>
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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; <…;
}
Stream<out A, out E = never, out R = never>.channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>(property) Stream<out A, out E = never, out R = never>.channel: {
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 ChannelChannel.flattenArray,
import ChannelChannel.mapEffect(f: (
a: A,
i: number
) => Effect.Effect<A2, E2, R2>
options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | undefined
}
| undefined
import ChannelChannel.map(import ArrArr.of),
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
))Referenced by 5 symbols