<E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(
self: Stream<A, E, R>
) => Stream<A | A2, E2, R2 | R>
<A, E, R, A2, E2, R2>(
self: Stream<A, E, R>,
f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>
): Stream<A | A2, E2, R | R2>Switches over to the stream produced by the provided function in case this one fails. Allows recovery from all causes of failure, including interruption if the stream is uninterruptible.
Example (Catching stream causes)
import { Console, Effect, Stream } from "effect"
const stream = Stream.make(1, 2).pipe(
Stream.concat(Stream.fail("Oops!")),
Stream.concat(Stream.make(3, 4))
)
const recovered = stream.pipe(
Stream.catchCause(() => Stream.make(999))
)
const program = Effect.gen(function*() {
const values = yield* Stream.runCollect(recovered)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2, 999 ]export const const catchCause: {
<E, A2, E2, R2>(
f: (
cause: Cause.Cause<E>
) => Stream<A2, E2, R2>
): <A, R>(
self: Stream<A, E, R>
) => Stream<A | A2, E2, R2 | R>
<A, E, R, A2, E2, R2>(
self: Stream<A, E, R>,
f: (
cause: Cause.Cause<E>
) => Stream<A2, E2, R2>
): Stream<A | A2, E2, R | R2>
}
Switches over to the stream produced by the provided function in case this
one fails. Allows recovery from all causes of failure, including
interruption if the stream is uninterruptible.
Example (Catching stream causes)
import { Console, Effect, Stream } from "effect"
const stream = Stream.make(1, 2).pipe(
Stream.concat(Stream.fail("Oops!")),
Stream.concat(Stream.make(3, 4))
)
const recovered = stream.pipe(
Stream.catchCause(() => Stream.make(999))
)
const program = Effect.gen(function*() {
const values = yield* Stream.runCollect(recovered)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2, 999 ]
catchCause: {
<function (type parameter) E in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>E, function (type parameter) A2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>A2, function (type parameter) E2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>E2, function (type parameter) R2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>R2>(
f: (
cause: Cause.Cause<E>
) => Stream<A2, E2, R2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.interface Cause<out E>A structured representation of how an Effect failed.
When to use
Use to preserve the full structured failure information for an effect instead
of collapsing it to a single error value.
Details
Access the individual failure entries through the reasons array, then
narrow each entry with
isFailReason
,
isDieReason
, or
- Use
hasFails
/
hasDies
/
hasInterrupts
to test
for the presence of specific reason kinds without iterating.
- Use
findError
/
findDefect
to extract the first value
of a given kind.
- Use
combine
to merge two causes.
Cause implements Equal — two causes with the same reasons (by value)
compare as equal.
Example (Creating and inspecting a cause)
import { Cause } from "effect"
const cause = Cause.fail("Something went wrong")
console.log(cause.reasons.length) // 1
console.log(Cause.isFailReason(cause.reasons[0])) // true
Companion namespace for the Cause interface.
Cause<function (type parameter) E in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>E>) => 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 <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>A2, function (type parameter) E2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>E2, function (type parameter) R2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>R2>
): <function (type parameter) A in <A, R>(self: Stream<A, E, R>): Stream<A | A2, E2, R2 | R>A, function (type parameter) R in <A, R>(self: Stream<A, E, R>): Stream<A | A2, 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 | A2, E2, R2 | R>A, function (type parameter) E in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>E, function (type parameter) R in <A, R>(self: Stream<A, E, R>): Stream<A | A2, 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 | A2, E2, R2 | R>A | function (type parameter) A2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>A2, function (type parameter) E2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>E2, function (type parameter) R2 in <E, A2, E2, R2>(f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): <A, R>(self: Stream<A, E, R>) => Stream<A | A2, E2, R2 | R>R2 | function (type parameter) R in <A, R>(self: Stream<A, E, R>): Stream<A | A2, E2, R2 | R>R>
<function (type parameter) A in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A, function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E, function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>R, function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A2, function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E2, function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>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: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A, function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E, function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>R>,
f: (
cause: Cause.Cause<E>
) => Stream<A2, E2, R2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.interface Cause<out E>A structured representation of how an Effect failed.
When to use
Use to preserve the full structured failure information for an effect instead
of collapsing it to a single error value.
Details
Access the individual failure entries through the reasons array, then
narrow each entry with
isFailReason
,
isDieReason
, or
- Use
hasFails
/
hasDies
/
hasInterrupts
to test
for the presence of specific reason kinds without iterating.
- Use
findError
/
findDefect
to extract the first value
of a given kind.
- Use
combine
to merge two causes.
Cause implements Equal — two causes with the same reasons (by value)
compare as equal.
Example (Creating and inspecting a cause)
import { Cause } from "effect"
const cause = Cause.fail("Something went wrong")
console.log(cause.reasons.length) // 1
console.log(Cause.isFailReason(cause.reasons[0])) // true
Companion namespace for the Cause interface.
Cause<function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E>) => 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: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A2, function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E2, function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>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, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A | function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A2, function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E2, function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>R | function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>R2>
} = dual<(...args: Array<any>) => any, <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>) => Stream<A | A2, E2, R | R2>>(arity: 2, body: <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>) => Stream<A | A2, E2, R | R2>): ((...args: Array<any>) => any) & (<A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>) => Stream<A | A2, E2, R | R2>) (+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, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A, function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E, function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>R, function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A2, function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E2, function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>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: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A, function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E, function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>R>,
f: (
cause: Cause.Cause<E>
) => Stream<A2, E2, R2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.interface Cause<out E>A structured representation of how an Effect failed.
When to use
Use to preserve the full structured failure information for an effect instead
of collapsing it to a single error value.
Details
Access the individual failure entries through the reasons array, then
narrow each entry with
isFailReason
,
isDieReason
, or
- Use
hasFails
/
hasDies
/
hasInterrupts
to test
for the presence of specific reason kinds without iterating.
- Use
findError
/
findDefect
to extract the first value
of a given kind.
- Use
combine
to merge two causes.
Cause implements Equal — two causes with the same reasons (by value)
compare as equal.
Example (Creating and inspecting a cause)
import { Cause } from "effect"
const cause = Cause.fail("Something went wrong")
console.log(cause.reasons.length) // 1
console.log(Cause.isFailReason(cause.reasons[0])) // true
Companion namespace for the Cause interface.
Cause<function (type parameter) E in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E>) => 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: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A2, function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E2, function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>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, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A | function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>A2, function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>E2, function (type parameter) R in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>R | function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Stream<A, E, R>, f: (cause: Cause.Cause<E>) => Stream<A2, E2, R2>): Stream<A | A2, E2, R | R2>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<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; <…;
}
Pipeable.pipe<Channel.Channel<readonly [A, ...A[]], E, void, unknown, unknown, unknown, R>, Channel.Channel<readonly [A, ...A[]] | readonly [A2, ...A2[]], E2, void, unknown, unknown, unknown, R | R2>, Stream<A | A2, E2, R | R2>>(this: Channel.Channel<...>, ab: (_: Channel.Channel<readonly [A, ...A[]], E, void, unknown, unknown, unknown, R>) => Channel.Channel<readonly [A, ...A[]] | readonly [A2, ...A2[]], E2, void, unknown, unknown, unknown, R | R2>, bc: (_: Channel.Channel<readonly [A, ...A[]] | readonly [A2, ...A2[]], E2, void, unknown, unknown, unknown, R | R2>) => Stream<A | A2, E2, R | R2>): Stream<...> (+21 overloads)pipe(
import ChannelChannel.const catchCause: {
<
OutErr,
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>(
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
): <
OutElem,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
Env | Env1
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
): Channel<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
Env | Env1
>
}
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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;
}
f: (
cause: Cause.Cause<E>
) => Stream<A2, E2, R2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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;
}
Stream<A2, E2, R2>.channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>(property) Stream<A2, E2, R2>.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; <…;
}
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
))