<A, E, R, EX, RX>(
pull: Effect.Effect<
Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>,
EX,
RX
>
): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>Creates a stream from a pull effect, such as one produced by Stream.toPull.
Details
A pull effect yields chunks on demand and completes when the upstream stream ends.
See Stream.toPull for a matching producer.
Example (Creating a stream from a pull effect)
import { Console, Effect, Stream } from "effect"
const program = Effect.scoped(
Effect.gen(function*() {
const source = Stream.make(1, 2, 3)
const pull = yield* Stream.toPull(source)
const stream = Stream.fromPull(Effect.succeed(pull))
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
)
Effect.runPromise(program)
// Output: [1, 2, 3]export const const fromPull: <A, E, R, EX, RX>(
pull: Effect.Effect<
Pull.Pull<
Arr.NonEmptyReadonlyArray<A>,
E,
void,
R
>,
EX,
RX
>
) => Stream<A, Pull.ExcludeDone<E> | EX, R | RX>
Creates a stream from a pull effect, such as one produced by Stream.toPull.
Details
A pull effect yields chunks on demand and completes when the upstream stream ends.
See Stream.toPull for a matching producer.
Example (Creating a stream from a pull effect)
import { Console, Effect, Stream } from "effect"
const program = Effect.scoped(
Effect.gen(function*() {
const source = Stream.make(1, 2, 3)
const pull = yield* Stream.toPull(source)
const stream = Stream.fromPull(Effect.succeed(pull))
const values = yield* Stream.runCollect(stream)
yield* Console.log(values)
})
)
Effect.runPromise(program)
// Output: [1, 2, 3]
fromPull = <function (type parameter) A in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>A, function (type parameter) E in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>E, function (type parameter) R in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>R, function (type parameter) EX in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>EX, function (type parameter) RX in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>RX>(
pull: Effect.Effect<
Pull.Pull<
Arr.NonEmptyReadonlyArray<A>,
E,
void,
R
>,
EX,
RX
>
(parameter) pull: {
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 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<import PullPull.interface Pull<out A, out E = never, out Done = void, out R = never>An effectful pull step that either produces a value, fails with E, or
signals completion with Cause.Done<Done>.
When to use
Use to model one low-level pull step when a consumer repeatedly evaluates an
effect that may emit a value, fail normally, or signal normal completion
through Cause.Done.
Details
Pull represents completion in the error channel so low-level stream
consumers can distinguish ordinary failures from end-of-input and carry a
leftover value when needed.
Pull<import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) A in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>A>, function (type parameter) E in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>E, void, function (type parameter) R in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>R>, function (type parameter) EX in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>EX, function (type parameter) RX in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<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>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>A, import PullPull.type ExcludeDone<E> =
E extends Cause.Done<any> ? never : E
Excludes Cause.Done completion signals from an error type union.
When to use
Use to describe the ordinary error type that remains after Cause.Done
completion signals have been handled or filtered out of an error union.
ExcludeDone<function (type parameter) E in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>E> | function (type parameter) EX in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>EX, function (type parameter) R in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<E> | EX, R | RX>R | function (type parameter) RX in <A, E, R, EX, RX>(pull: Effect.Effect<Pull.Pull<Arr.NonEmptyReadonlyArray<A>, E, void, R>, EX, RX>): Stream<A, Pull.ExcludeDone<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.const fromPull: <
OutElem,
OutErr,
OutDone,
EX,
EnvX,
Env
>(
effect: Effect.Effect<
Pull.Pull<OutElem, OutErr, OutDone, EnvX>,
EX,
Env
>
) => Channel<
OutElem,
Pull.ExcludeDone<OutErr> | EX,
OutDone,
unknown,
unknown,
unknown,
Env | EnvX
>
Creates a Channel from an Effect that produces a Pull.
Example (Creating channels from pulls)
import { Channel, Effect } from "effect"
const channel = Channel.fromPull(
Effect.succeed(Effect.succeed(42))
)
fromPull(pull: Effect.Effect<
Pull.Pull<
Arr.NonEmptyReadonlyArray<A>,
E,
void,
R
>,
EX,
RX
>
(parameter) pull: {
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;
}