<A, Pass, Fail>(
filter: Filter.Filter<NoInfer<A>, Pass, Fail>,
options?: { readonly bufferSize?: number | undefined }
): <E, R>(
self: Stream<A, E, R>
) => Effect.Effect<
[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>],
never,
R | Scope.Scope
>
<A, E, R, Pass, Fail>(
self: Stream<A, E, R>,
filter: Filter.Filter<NoInfer<A>, Pass, Fail>,
options?: { readonly bufferSize?: number | undefined }
): Effect.Effect<
[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>],
never,
R | Scope.Scope
>Splits a stream into scoped excluded and satisfying substreams using a
Filter.
Details
The returned streams are backed by queues in the current scope and should be
consumed while that scope remains open. The faster stream may advance up to
bufferSize elements ahead of the slower one.
Example (Partitioning a stream)
import { Console, Effect, Result, Stream } from "effect"
const program = Effect.gen(function*() {
const [excluded, satisfying] = yield* Stream.partition(
Stream.make(1, 2, 3, 4),
(n) => n % 2 === 0 ? Result.succeed(n) : Result.fail(n)
)
const left = yield* Stream.runCollect(excluded)
const right = yield* Stream.runCollect(satisfying)
yield* Console.log(left)
// Output: [ 1, 3 ]
yield* Console.log(right)
// Output: [ 2, 4 ]
})export const const partition: {
<A, Pass, Fail>(
filter: Filter.Filter<NoInfer<A>, Pass, Fail>,
options?: {
readonly bufferSize?: number | undefined
}
): <E, R>(
self: Stream<A, E, R>
) => Effect.Effect<
[
excluded: Stream<Fail, E>,
satisfying: Stream<Pass, E>
],
never,
R | Scope.Scope
>
<A, E, R, Pass, Fail>(
self: Stream<A, E, R>,
filter: Filter.Filter<NoInfer<A>, Pass, Fail>,
options?: {
readonly bufferSize?: number | undefined
}
): Effect.Effect<
[
excluded: Stream<Fail, E>,
satisfying: Stream<Pass, E>
],
never,
R | Scope.Scope
>
}
Splits a stream into scoped excluded and satisfying substreams using a
Filter.
Details
The returned streams are backed by queues in the current scope and should be
consumed while that scope remains open. The faster stream may advance up to
bufferSize elements ahead of the slower one.
Example (Partitioning a stream)
import { Console, Effect, Result, Stream } from "effect"
const program = Effect.gen(function*() {
const [excluded, satisfying] = yield* Stream.partition(
Stream.make(1, 2, 3, 4),
(n) => n % 2 === 0 ? Result.succeed(n) : Result.fail(n)
)
const left = yield* Stream.runCollect(excluded)
const right = yield* Stream.runCollect(satisfying)
yield* Console.log(left)
// Output: [ 1, 3 ]
yield* Console.log(right)
// Output: [ 2, 4 ]
})
partition: {
<function (type parameter) A in <A, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Pass in <A, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Fail in <A, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
filter: Filter.Filter<NoInfer<A>, Pass, Fail>filter: import FilterFilter.interface Filter<in Input, out Pass = Input, out Fail = Input>Represents a filter function that can transform inputs to outputs or filter them out.
Details
A filter takes an input value and either returns a boxed pass value or the
special fail type to indicate the value should be filtered out.
Example (Defining a positive number filter)
import { Filter, Result } from "effect"
// A filter that only passes positive numbers
const positiveFilter: Filter.Filter<number> = (n) => n > 0 ? Result.succeed(n) : Result.fail(n)
console.log(positiveFilter(5)) // Result.succeed(5)
console.log(positiveFilter(-3)) // Result.fail(-3)
Filter<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, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Pass in <A, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Fail in <A, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
options: | {
readonly bufferSize?: number | undefined
}
| undefined
bufferSize?: number | undefinedbufferSize?: number | undefined }
): <function (type parameter) E in <E, R>(self: Stream<A, E, R>): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>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, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>R>
) => import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<
[Stream<Fail, E, 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
excluded: 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) Fail in <A, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>E>, Stream<Pass, E, 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
satisfying: 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) Pass in <A, Pass, Fail>(filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): <E, R>(self: Stream<A, E, R>) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>E>],
never,
function (type parameter) R in <E, R>(self: Stream<A, E, R>): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>R | import ScopeScope.Scope
>
<function (type parameter) A in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) R in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Pass in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Fail in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
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, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) R in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
filter: Filter.Filter<NoInfer<A>, Pass, Fail>filter: import FilterFilter.interface Filter<in Input, out Pass = Input, out Fail = Input>Represents a filter function that can transform inputs to outputs or filter them out.
Details
A filter takes an input value and either returns a boxed pass value or the
special fail type to indicate the value should be filtered out.
Example (Defining a positive number filter)
import { Filter, Result } from "effect"
// A filter that only passes positive numbers
const positiveFilter: Filter.Filter<number> = (n) => n > 0 ? Result.succeed(n) : Result.fail(n)
console.log(positiveFilter(5)) // Result.succeed(5)
console.log(positiveFilter(-3)) // Result.fail(-3)
Filter<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, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Pass in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Fail in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
options: | {
readonly bufferSize?: number | undefined
}
| undefined
bufferSize?: number | undefinedbufferSize?: number | undefined }
): import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<
[Stream<Fail, E, 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
excluded: 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) Fail in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
Stream<Pass, E, 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
satisfying: 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) Pass in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) R in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
import ScopeScope.Scope
>
} = dual<(...args: Array<any>) => any, <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>>(isDataFirst: (args: IArguments) => boolean, body: <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>): ((...args: Array<any>) => any) & (<A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}) => Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>) (+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(
(args: IArgumentsargs) => const isStream: (
u: unknown
) => u is Stream<unknown, unknown, unknown>
Checks whether a value is a Stream.
Example (Checking whether a value is a Stream)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.make(1, 2, 3)
const notStream = { data: [1, 2, 3] }
yield* Console.log(Stream.isStream(stream))
// true
yield* Console.log(Stream.isStream(notStream))
// false
})
Effect.runPromise(program)
isStream(args: IArgumentsargs[0]),
<function (type parameter) A in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) R in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Pass in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Fail in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
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, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) R in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
filter: Filter.Filter<NoInfer<A>, Pass, Fail>filter: import FilterFilter.interface Filter<in Input, out Pass = Input, out Fail = Input>Represents a filter function that can transform inputs to outputs or filter them out.
Details
A filter takes an input value and either returns a boxed pass value or the
special fail type to indicate the value should be filtered out.
Example (Defining a positive number filter)
import { Filter, Result } from "effect"
// A filter that only passes positive numbers
const positiveFilter: Filter.Filter<number> = (n) => n > 0 ? Result.succeed(n) : Result.fail(n)
console.log(positiveFilter(5)) // Result.succeed(5)
console.log(positiveFilter(-3)) // Result.fail(-3)
Filter<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, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Pass in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) Fail in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
options: | {
readonly bufferSize?: number | undefined
}
| undefined
bufferSize?: number | undefinedbufferSize?: number | undefined }
): import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<
[Stream<Fail, E, 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
excluded: 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) Fail in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
Stream<Pass, E, 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
satisfying: 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) Pass in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) E in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
function (type parameter) R in <A, E, R, Pass, Fail>(self: Stream<A, E, R>, filter: Filter.Filter<NoInfer<A>, Pass, Fail>, options?: {
readonly bufferSize?: number | undefined;
}): Effect.Effect<[excluded: Stream<Fail, E>, satisfying: Stream<Pass, E>], never, R | Scope.Scope>
import ScopeScope.Scope
> =>
import EffectEffect.const map: {
<A, B>(f: (a: A) => B): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E, R>
<A, E, R, B>(
self: Effect<A, E, R>,
f: (a: A) => B
): Effect<B, E, R>
}
const partitionQueue: {
<A, Pass, Fail>(
filter: Filter.Filter<NoInfer<A>, Pass, Fail>,
options?: {
readonly capacity?:
| number
| "unbounded"
| undefined
}
): <E, R>(
self: Stream<A, E, R>
) => Effect.Effect<
[
passes: Queue.Dequeue<Pass, E | Cause.Done>,
fails: Queue.Dequeue<Fail, E | Cause.Done>
],
never,
R | Scope.Scope
>
<A, E, R, Pass, Fail>(
self: Stream<A, E, R>,
filter: Filter.Filter<NoInfer<A>, Pass, Fail>,
options?: {
readonly capacity?:
| number
| "unbounded"
| undefined
}
): Effect.Effect<
[
passes: Queue.Dequeue<Pass, E | Cause.Done>,
fails: Queue.Dequeue<Fail, E | Cause.Done>
],
never,
R | Scope.Scope
>
}
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; <…;
}
filter: Filter.Filter<NoInfer<A>, Pass, Fail>filter, { capacity?: number | "unbounded" | undefinedcapacity: options: | {
readonly bufferSize?: number | undefined
}
| undefined
bufferSize?: number | undefinedbufferSize ?? 16 }),
([passes: Queue.Dequeue<
Pass,
Cause.Done<void> | E
>
(parameter) passes: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
fails: Queue.Dequeue<
Fail,
Cause.Done<void> | E
>
(parameter) fails: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
const fromQueue: <A, E>(
queue: Queue.Dequeue<A, E>
) => Stream<A, Exclude<E, Cause.Done>>
Creates a stream that pulls values from a Queue.Dequeue.
Details
The stream emits non-empty batches of queued values and ends when the queue
fails with Cause.Done; other queue failures are propagated.
Example (Creating a stream from a queue of values)
import { Console, Effect, Queue, Stream } from "effect"
const program = Effect.gen(function*() {
const queue = yield* Queue.unbounded<number>()
yield* Queue.offer(queue, 1)
yield* Queue.offer(queue, 2)
yield* Queue.offer(queue, 3)
yield* Queue.shutdown(queue)
const stream = Stream.fromQueue(queue)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2, 3 ]
fromQueue(fails: Queue.Dequeue<
Fail,
Cause.Done<void> | E
>
(parameter) fails: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
const fromQueue: <A, E>(
queue: Queue.Dequeue<A, E>
) => Stream<A, Exclude<E, Cause.Done>>
Creates a stream that pulls values from a Queue.Dequeue.
Details
The stream emits non-empty batches of queued values and ends when the queue
fails with Cause.Done; other queue failures are propagated.
Example (Creating a stream from a queue of values)
import { Console, Effect, Queue, Stream } from "effect"
const program = Effect.gen(function*() {
const queue = yield* Queue.unbounded<number>()
yield* Queue.offer(queue, 1)
yield* Queue.offer(queue, 2)
yield* Queue.offer(queue, 3)
yield* Queue.shutdown(queue)
const stream = Stream.fromQueue(queue)
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
Effect.runPromise(program)
// Output: [ 1, 2, 3 ]
fromQueue(passes: Queue.Dequeue<
Pass,
Cause.Done<void> | E
>
(parameter) passes: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
type const = [Stream<Fail, Exclude<E, Cause.Done<void>>, never>, Stream<Pass, Exclude<E, Cause.Done<void>>, never>]const
)
)