<A, E2, R2>(
predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>
): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>
<A, E, R, E2, R2>(
self: Stream<A, E, R>,
predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>
): Stream<A, E | E2, R | R2>Takes elements from the stream while the effectful predicate is true.
When to use
Use when the leading-prefix predicate needs an Effect or service and the stream should stop before the first false result.
Example (Effectfully taking while a predicate holds)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const result = yield* Stream.range(1, 5).pipe(
Stream.takeWhileEffect((n) => Effect.succeed(n % 3 !== 0)),
Stream.runCollect
)
Console.log(result)
})
Effect.runPromise(program)
// Output: [ 1, 2 ]filtering
Source effect/Stream.ts:664817 lines
export const const takeWhileEffect: {
<A, E2, R2>(
predicate: (
a: NoInfer<A>,
n: number
) => Effect.Effect<boolean, E2, R2>
): <E, R>(
self: Stream<A, E, R>
) => Stream<A, E | E2, R | R2>
<A, E, R, E2, R2>(
self: Stream<A, E, R>,
predicate: (
a: NoInfer<A>,
n: number
) => Effect.Effect<boolean, E2, R2>
): Stream<A, E | E2, R | R2>
}
Takes elements from the stream while the effectful predicate is true.
When to use
Use when the leading-prefix predicate needs an Effect or service and the
stream should stop before the first false result.
Example (Effectfully taking while a predicate holds)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const result = yield* Stream.range(1, 5).pipe(
Stream.takeWhileEffect((n) => Effect.succeed(n % 3 !== 0)),
Stream.runCollect
)
Console.log(result)
})
Effect.runPromise(program)
// Output: [ 1, 2 ]
takeWhileEffect: {
<function (type parameter) A in <A, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>A, function (type parameter) E2 in <A, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>E2, function (type parameter) R2 in <A, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>R2>(
predicate: (
a: NoInfer<A>,
n: number
) => Effect.Effect<boolean, E2, R2>
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, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>A>, n: numbern: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<boolean, function (type parameter) E2 in <A, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>E2, function (type parameter) R2 in <A, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>R2>
): <function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A, E | E2, R | R2>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<A, E | E2, R | R2>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, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>A, function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A, E | E2, R | R2>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<A, E | E2, R | R2>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, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>A, function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<A, E | E2, R | R2>E | function (type parameter) E2 in <A, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>E2, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<A, E | E2, R | R2>R | function (type parameter) R2 in <A, E2, R2>(predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): <E, R>(self: Stream<A, E, R>) => Stream<A, E | E2, R | R2>R2>
<function (type parameter) A in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>A, function (type parameter) E in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>E, function (type parameter) R in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>R, function (type parameter) E2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>E2, function (type parameter) R2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | 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, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>A, function (type parameter) E in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>E, function (type parameter) R in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>R>,
predicate: (
a: NoInfer<A>,
n: number
) => Effect.Effect<boolean, E2, R2>
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, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>A>, n: numbern: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<boolean, function (type parameter) E2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>E2, function (type parameter) R2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | 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, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>A, function (type parameter) E in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>E | function (type parameter) E2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>E2, function (type parameter) R in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>R | function (type parameter) R2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, E | E2, R | R2>R2>
} = import dualdual(2, <function (type parameter) A in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>A, function (type parameter) E in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>E, function (type parameter) R in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>R, function (type parameter) E2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>E2, function (type parameter) R2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>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, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>A, function (type parameter) E in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>E, function (type parameter) R in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>R>,
predicate: (
a: NoInfer<A>,
n: number
) => Effect.Effect<boolean, E2, R2>
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, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>A>, n: numbern: number) => import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<boolean, function (type parameter) E2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>E2, function (type parameter) R2 in <A, E, R, E2, R2>(self: Stream<A, E, R>, predicate: (a: NoInfer<A>, n: number) => Effect.Effect<boolean, E2, R2>): Stream<A, unknown, unknown>R2>
) =>
const takeUntilEffect: {
<A, E2, R2>(
predicate: (
a: NoInfer<A>,
n: number
) => Effect.Effect<boolean, E2, R2>,
options?: {
readonly excludeLast?: boolean | undefined
}
): <E, R>(
self: Stream<A, E, R>
) => Stream<A, E2 | E, R2 | R>
<A, E, R, E2, R2>(
self: Stream<A, E, R>,
predicate: (
a: A,
n: number
) => Effect.Effect<boolean, E2, R2>,
options?: {
readonly excludeLast?: boolean | undefined
}
): Stream<A, E | E2, R | R2>
}
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
a: Aa, n: numbern) =>
import EffectEffect.map(
predicate: (
a: NoInfer<A>,
n: number
) => Effect.Effect<boolean, E2, R2>
a: Aa, n: numbern),
(b: anyb) => !b: anyb
), { excludeLast?: boolean | undefinedexcludeLast: true }))