<A, EX, RX>(
predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>
): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>
<A, E, R, EX, RX>(
self: Stream<A, E, R>,
predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>
): Stream<A, E | EX, R | RX>Filters elements in a single pass effectfully.
Example (Effectfully filtering stream values)
import { Console, Effect, Stream } from "effect"
const stream = Stream.make(1, 2, 3, 4).pipe(Stream.filterEffect((n) => Effect.succeed(n > 2)))
const program = Effect.gen(function*() {
const result = yield* Stream.runCollect(stream)
yield* Console.log(result)
})
Effect.runPromise(program)
// Output: [ 3, 4 ]filtering
Source effect/Stream.ts:437915 lines
export const const filterEffect: {
<A, EX, RX>(
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, EX, RX>
): <E, R>(
self: Stream<A, E, R>
) => Stream<A, E | EX, R | RX>
<A, E, R, EX, RX>(
self: Stream<A, E, R>,
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, EX, RX>
): Stream<A, E | EX, R | RX>
}
Filters elements in a single pass effectfully.
Example (Effectfully filtering stream values)
import { Console, Effect, Stream } from "effect"
const stream = Stream.make(1, 2, 3, 4).pipe(Stream.filterEffect((n) => Effect.succeed(n > 2)))
const program = Effect.gen(function*() {
const result = yield* Stream.runCollect(stream)
yield* Console.log(result)
})
Effect.runPromise(program)
// Output: [ 3, 4 ]
filterEffect: {
<function (type parameter) A in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>A, function (type parameter) EX in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>RX>(
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, EX, RX>
a: NoInfer<A>a: 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) A in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>A>, i: numberi: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<boolean, function (type parameter) EX in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>RX>
): <function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <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, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>A, function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <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, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>A, function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>E | function (type parameter) EX in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>EX, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<A, E | EX, R | RX>R | function (type parameter) RX in <A, EX, RX>(predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | EX, R | RX>RX>
<function (type parameter) A in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>R, function (type parameter) EX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, 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, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>R>,
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, EX, RX>
a: NoInfer<A>a: 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) A in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A>, i: numberi: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<boolean, function (type parameter) EX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, 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, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>E | function (type parameter) EX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) R in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>R | function (type parameter) RX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>RX>
} = import dualdual(
2,
<function (type parameter) A in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>R, function (type parameter) EX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, 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, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>E, function (type parameter) R in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>R>,
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, EX, RX>
a: NoInfer<A>a: 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) A in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A>, i: numberi: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<boolean, function (type parameter) EX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) RX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, 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, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>A, function (type parameter) E in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>E | function (type parameter) EX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>EX, function (type parameter) R in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, EX, RX>): Stream<A, E | EX, R | RX>R | function (type parameter) RX in <A, E, R, EX, RX>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, i: number) => Effect.Effect<boolean, 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.filterArrayEffect(const toChannel: <A, E, R>(
stream: Stream<A, E, R>
) => Channel.Channel<
Arr.NonEmptyReadonlyArray<A>,
E,
void,
unknown,
unknown,
unknown,
R
>
Creates a channel from a stream.
Example (Converting a stream to a channel)
import { Channel, Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.make(1, 2, 3)
const channel = Stream.toChannel(stream)
const values = yield* Channel.runCollect(channel)
yield* Console.log(values.flat())
})
Effect.runPromise(program)
// Output: [ 1, 2, 3 ]
toChannel(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; <…;
}
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, EX, RX>