<E, X, E2, R2>(
policy:
| Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)
): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>
<A, E, R, X, E2, R2>(
self: Stream<A, E, R>,
policy:
| Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)
): Stream<A, E | E2, R2 | R>Retries the stream according to the given schedule when it fails.
Details
This retries the entire stream, so will re-execute all of the stream's acquire operations.
The schedule is reset as soon as the first element passes through the stream again.
Example (Retrying stream failures)
import { Console, Effect, Schedule, Stream } from "effect"
const program = Effect.gen(function*() {
const values = yield* Stream.make(1).pipe(
Stream.concat(Stream.fail("boom")),
Stream.retry(Schedule.recurs(1)),
Stream.take(2),
Stream.runCollect
)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 1 ]error handling
Source effect/Stream.ts:614527 lines
export const const retry: {
<E, X, E2, R2>(
policy:
| Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<
X,
NoInfer<E>,
E2,
R2
>)
): <A, R>(
self: Stream<A, E, R>
) => Stream<A, E | E2, R2 | R>
<A, E, R, X, E2, R2>(
self: Stream<A, E, R>,
policy:
| Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<
X,
NoInfer<E>,
E2,
R2
>)
): Stream<A, E | E2, R2 | R>
}
Retries the stream according to the given schedule when it fails.
Details
This retries the entire stream, so will re-execute all of the stream's
acquire operations.
The schedule is reset as soon as the first element passes through the
stream again.
Example (Retrying stream failures)
import { Console, Effect, Schedule, Stream } from "effect"
const program = Effect.gen(function*() {
const values = yield* Stream.make(1).pipe(
Stream.concat(Stream.fail("boom")),
Stream.retry(Schedule.recurs(1)),
Stream.take(2),
Stream.runCollect
)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 1 ]
retry: {
<function (type parameter) E in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E, function (type parameter) X in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>X, function (type parameter) E2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>R2>(
policy: | Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)
import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) X in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>X, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E>, function (type parameter) E2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>
) => Schedule.Schedule<SO, E, SE, SR>
function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>(_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
(parameter) _: {
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 ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E>, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>) => import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, function (type parameter) E in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>
) => import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) X in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>X, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E>, function (type parameter) E2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>R2>)
): <function (type parameter) A in <A, R>(self: Stream<A, E, R>): Stream<A, E | E2, R2 | R>A, function (type parameter) R in <A, R>(self: Stream<A, E, R>): Stream<A, E | E2, R2 | R>R>(self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, R>(self: Stream<A, E, R>): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E, function (type parameter) R in <A, R>(self: Stream<A, E, R>): Stream<A, E | E2, 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) A in <A, R>(self: Stream<A, E, R>): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E | function (type parameter) E2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <E, X, E2, R2>(policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): <A, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R2 | R>R2 | function (type parameter) R in <A, R>(self: Stream<A, E, R>): Stream<A, E | E2, R2 | R>R>
<function (type parameter) A in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E, function (type parameter) R in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R, function (type parameter) X in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>X, function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2>(
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E, function (type parameter) R in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R>,
policy: | Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)
import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) X in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>X, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E>, function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>
) => Schedule.Schedule<SO, E, SE, SR>
function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>(_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
(parameter) _: {
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 ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E>, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>) => import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>
) => import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) X in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>X, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E>, function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2>)
): interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E | function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2 | function (type parameter) R in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R>
} = dual<(...args: Array<any>) => any, <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)) => Stream<A, E | E2, R2 | R>>(arity: 2, body: <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)) => Stream<A, E | E2, R2 | R>): ((...args: Array<any>) => any) & (<A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)) => Stream<A, E | E2, R2 | R>) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(
2,
<function (type parameter) A in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E, function (type parameter) R in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R, function (type parameter) X in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>X, function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2>(
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E, function (type parameter) R in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R>,
policy: | Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)
import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) X in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>X, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E>, function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>
) => Schedule.Schedule<SO, E, SE, SR>
function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>(_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
(parameter) _: {
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 ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E>, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>) => import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SO, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E, function (type parameter) SE in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SE, function (type parameter) SR in <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>): Schedule.Schedule<SO, E, SE, SR>SR>
) => import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) X in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>X, type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E>, function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2>)
): interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>A, function (type parameter) E in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E | function (type parameter) E2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>E2, function (type parameter) R2 in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R2 | function (type parameter) R in <A, E, R, X, E2, R2>(self: Stream<A, E, R>, policy: Schedule.Schedule<X, NoInfer<E>, E2, R2> | (($: <SO, SE, SR>(_: Schedule.Schedule<SO, NoInfer<E>, SE, SR>) => Schedule.Schedule<SO, E, SE, SR>) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)): Stream<A, E | E2, R2 | R>R> => 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.const retry: {
<SO, OutErr, SE, SR>(
schedule:
| Schedule.Schedule<
SO,
Types.NoInfer<OutErr>,
SE,
SR
>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
Types.NoInfer<OutErr>,
SE,
SR
>
) => Schedule.Schedule<
SO,
OutErr,
SE,
SR
>
) => Schedule.Schedule<
SO,
Types.NoInfer<OutErr>,
SE,
SR
>)
): <
OutElem,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr | SE,
OutDone,
InElem,
InErr,
InDone,
Env | SR
>
) => Channel<
OutElem,
OutErr | SE,
OutDone,
InElem,
InErr,
InDone,
Env | SR
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
SO,
SE,
SR
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
schedule:
| Schedule.Schedule<SO, OutErr, SE, SR>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
Types.NoInfer<OutErr>,
SE,
SR
>
) => Schedule.Schedule<
SO,
OutErr,
SE,
SR
>
) => Schedule.Schedule<
SO,
Types.NoInfer<OutErr>,
SE,
SR
>)
): Channel<
OutElem,
OutErr | SE,
OutDone,
InElem,
InErr,
InDone,
Env | SR
>
}
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<A, E, R>.channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>(property) Stream<A, E, R>.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; <…;
}
policy: | Schedule.Schedule<X, NoInfer<E>, E2, R2>
| ((
$: <SO, SE, SR>(
_: Schedule.Schedule<
SO,
NoInfer<E>,
SE,
SR
>
) => Schedule.Schedule<SO, E, SE, SR>
) => Schedule.Schedule<X, NoInfer<E>, E2, R2>)
Referenced by 1 symbols