<X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(
self: Stream<A, E, R>
) => Stream<A, E | EX, R | RX>
<A, E, R, X, EX, RX>(
self: Stream<A, E, R>,
onStart: Effect.Effect<X, EX, RX>
): Stream<A, E | EX, R | RX>Runs the provided effect before this stream starts.
Example (Running an effect on start)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.fromArray([1, 2, 3]).pipe(
Stream.onStart(Console.log("Stream started"))
)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output:
// Stream started
// [1, 2, 3]sequencing
Source effect/Stream.ts:987912 lines
export const const onStart: {
<X, EX, RX>(
onStart: Effect.Effect<X, EX, RX>
): <A, E, R>(
self: Stream<A, E, R>
) => Stream<A, E | EX, R | RX>
<A, E, R, X, EX, RX>(
self: Stream<A, E, R>,
onStart: Effect.Effect<X, EX, RX>
): Stream<A, E | EX, R | RX>
}
Runs the provided effect before this stream starts.
Example (Running an effect on start)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.fromArray([1, 2, 3]).pipe(
Stream.onStart(Console.log("Stream started"))
)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output:
// Stream started
// [1, 2, 3]
onStart: {
<function (type parameter) X in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>X, function (type parameter) EX in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>RX>(
onStart: Effect.Effect<X, EX, RX>(parameter) onStart: {
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<function (type parameter) X in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>X, function (type parameter) EX in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>RX>
): <function (type parameter) A in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>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, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>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>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>E | function (type parameter) EX in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>EX, function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>R | function (type parameter) RX in <X, EX, RX>(onStart: Effect.Effect<X, EX, RX>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>RX>
<function (type parameter) A in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>R, function (type parameter) X in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>X, function (type parameter) EX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>RX>(
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, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>R>,
onStart: Effect.Effect<X, EX, RX>(parameter) onStart: {
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<function (type parameter) X in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>X, function (type parameter) EX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>RX>
): 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, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>E | function (type parameter) EX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) R in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>R | function (type parameter) RX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>RX>
} = import dualdual(2, <function (type parameter) A in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>R, function (type parameter) X in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>X, function (type parameter) EX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>RX>(
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, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>R>,
onStart: Effect.Effect<X, EX, RX>(parameter) onStart: {
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<function (type parameter) X in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>X, function (type parameter) EX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>RX>
): 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, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>E | function (type parameter) EX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) R in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>R | function (type parameter) RX in <A, E, R, X, EX, RX>(self: Stream<A, E, R>, onStart: Effect.Effect<X, EX, RX>): Stream<A, E | EX, R | RX>RX> => 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.onStart(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; <…;
}
onStart: Effect.Effect<X, EX, RX>(parameter) onStart: {
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;
}