<A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(
acquire: Effect.Effect<A, E, R>,
use: (
a: A
) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
release: (
a: A,
exit: Exit.Exit<OutDone, OutErr>
) => Effect.Effect<unknown>
): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>Acquires a resource, uses it to build a Channel, and guarantees that
release runs with the channel's Exit when the channel completes, fails,
or is interrupted.
Details
Acquisition is uninterruptible. If acquisition fails, use is not run and
release is not registered.
Example (Managing resources with acquire-use-release)
import { Channel, Effect } from "effect"
const channel = Channel.acquireUseRelease(
Effect.succeed("resource"),
(resource) => Channel.succeed(resource.toUpperCase()),
(resource, exit) => Effect.log(`Released: ${resource}`)
)constructors
Source effect/Channel.ts:56417 lines
export const const acquireUseRelease: <
A,
E,
R,
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
acquire: Effect.Effect<A, E, R>,
use: (
a: A
) => Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
release: (
a: A,
exit: Exit.Exit<OutDone, OutErr>
) => Effect.Effect<unknown>
) => Channel<
OutElem,
OutErr | E,
OutDone,
InElem,
InErr,
InDone,
Env | R
>
Acquires a resource, uses it to build a Channel, and guarantees that
release runs with the channel's Exit when the channel completes, fails,
or is interrupted.
Details
Acquisition is uninterruptible. If acquisition fails, use is not run and
release is not registered.
Example (Managing resources with acquire-use-release)
import { Channel, Effect } from "effect"
const channel = Channel.acquireUseRelease(
Effect.succeed("resource"),
(resource) => Channel.succeed(resource.toUpperCase()),
(resource, exit) => Effect.log(`Released: ${resource}`)
)
acquireUseRelease = <function (type parameter) A in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>A, function (type parameter) E in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>E, function (type parameter) R in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>R, function (type parameter) OutElem in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutElem, function (type parameter) OutErr in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutErr, function (type parameter) OutDone in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutDone, function (type parameter) InElem in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InElem, function (type parameter) InErr in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InErr, function (type parameter) InDone in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InDone, function (type parameter) Env in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>Env>(
acquire: Effect.Effect<A, E, R>(parameter) acquire: {
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<function (type parameter) A in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>A, function (type parameter) E in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>E, function (type parameter) R in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>R>,
use: (
a: A
) => Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
a: Aa: function (type parameter) A in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>A) => interface Channel<out OutElem, out OutErr = never, out OutDone = void, in InElem = unknown, in InErr = unknown, in InDone = unknown, out Env = never>A Channel is a nexus of I/O operations, which supports both reading and
writing. A channel may read values of type InElem and write values of type
OutElem. When the channel finishes, it yields a value of type OutDone. A
channel may fail with a value of type OutErr.
Details
Channels are the foundation of Streams: both streams and sinks are built on
channels. Most users shouldn't have to use channels directly, as streams and
sinks are much more convenient and cover all common use cases. However, when
adding new stream and sink operators, or doing something highly specialized,
it may be useful to use channels directly.
Channels compose in a variety of ways:
- Piping: One channel can be piped to another channel, assuming the
input type of the second is the same as the output type of the first.
- Sequencing: The terminal value of one channel can be used to create
another channel, and both the first channel and the function that makes
the second channel can be composed into a channel.
- Concatenating: The output of one channel can be used to create other
channels, which are all concatenated together. The first channel and the
function that makes the other channels can be composed into a channel.
Example (Typing channels)
import type { Channel } from "effect"
// A channel that outputs numbers and requires no environment
type NumberChannel = Channel.Channel<number>
// A channel that outputs strings, can fail with Error, completes with boolean
type StringChannel = Channel.Channel<string, Error, boolean>
// A channel with all type parameters specified
type FullChannel = Channel.Channel<
string, // OutElem - output elements
Error, // OutErr - output errors
number, // OutDone - completion value
number, // InElem - input elements
string, // InErr - input errors
boolean, // InDone - input completion
{ db: string } // Env - required environment
>
Channel<function (type parameter) OutElem in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutElem, function (type parameter) OutErr in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutErr, function (type parameter) OutDone in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutDone, function (type parameter) InElem in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InElem, function (type parameter) InErr in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InErr, function (type parameter) InDone in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InDone, function (type parameter) Env in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>Env>,
release: (
a: A,
exit: Exit.Exit<OutDone, OutErr>
) => Effect.Effect<unknown>
a: Aa: function (type parameter) A in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>A, exit: Exit.Exit<OutDone, OutErr>exit: import ExitExit.type Exit<A, E = never> = Exit.Success<A, E> | Exit.Failure<A, E>Represents the result of an Effect computation.
When to use
Use when you need to synchronously inspect whether an Effect computation
succeeded or failed.
Details
An Exit<A, E> is either Success<A, E> containing a value of type A, or
Failure<A, E> containing a Cause<E> describing why the computation
failed.
Since Exit is also an Effect, you can yield it inside Effect.gen.
Example (Pattern matching on an Exit)
import { Exit } from "effect"
const success: Exit.Exit<number> = Exit.succeed(42)
const failure: Exit.Exit<number, string> = Exit.fail("error")
const result = Exit.match(success, {
onSuccess: (value) => `Got value: ${value}`,
onFailure: (cause) => `Got error: ${cause}`
})
Namespace containing helper types shared by Exit values.
When to use
Use to reference helper types that describe the shared structure of Exit
values.
Exit<function (type parameter) OutDone in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutDone, function (type parameter) OutErr in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutErr>) => 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<unknown>
): interface Channel<out OutElem, out OutErr = never, out OutDone = void, in InElem = unknown, in InErr = unknown, in InDone = unknown, out Env = never>A Channel is a nexus of I/O operations, which supports both reading and
writing. A channel may read values of type InElem and write values of type
OutElem. When the channel finishes, it yields a value of type OutDone. A
channel may fail with a value of type OutErr.
Details
Channels are the foundation of Streams: both streams and sinks are built on
channels. Most users shouldn't have to use channels directly, as streams and
sinks are much more convenient and cover all common use cases. However, when
adding new stream and sink operators, or doing something highly specialized,
it may be useful to use channels directly.
Channels compose in a variety of ways:
- Piping: One channel can be piped to another channel, assuming the
input type of the second is the same as the output type of the first.
- Sequencing: The terminal value of one channel can be used to create
another channel, and both the first channel and the function that makes
the second channel can be composed into a channel.
- Concatenating: The output of one channel can be used to create other
channels, which are all concatenated together. The first channel and the
function that makes the other channels can be composed into a channel.
Example (Typing channels)
import type { Channel } from "effect"
// A channel that outputs numbers and requires no environment
type NumberChannel = Channel.Channel<number>
// A channel that outputs strings, can fail with Error, completes with boolean
type StringChannel = Channel.Channel<string, Error, boolean>
// A channel with all type parameters specified
type FullChannel = Channel.Channel<
string, // OutElem - output elements
Error, // OutErr - output errors
number, // OutDone - completion value
number, // InElem - input elements
string, // InErr - input errors
boolean, // InDone - input completion
{ db: string } // Env - required environment
>
Channel<function (type parameter) OutElem in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutElem, function (type parameter) OutErr in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutErr | function (type parameter) E in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>E, function (type parameter) OutDone in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>OutDone, function (type parameter) InElem in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InElem, function (type parameter) InErr in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InErr, function (type parameter) InDone in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>InDone, function (type parameter) Env in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>Env | function (type parameter) R in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>R> =>
const fromTransformBracket: <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
EX,
EnvX,
Env
>(
f: (
upstream: Pull.Pull<InElem, InErr, InDone>,
scope: Scope.Scope,
forkedScope: Scope.Scope
) => Effect.Effect<
Pull.Pull<OutElem, OutErr, OutDone, EnvX>,
EX,
Env
>
) => Channel<
OutElem,
Pull.ExcludeDone<OutErr> | EX,
OutDone,
InElem,
InErr,
InDone,
Env | EnvX
>
Creates a Channel from a transformation function that operates on upstream
pulls, but also provides a forked scope that closes when the resulting
Channel completes.
When to use
Use when building channels that require scoped resource lifecycle management,
providing both the channel scope and a forked scope that automatically closes
when the channel completes.
fromTransformBracket(
import EffectEffect.const fnUntraced: <Effect.Effect<void, never, never> | Effect.Effect<A, E, R> | Effect.Effect<Pull.Pull<OutElem, OutErr, OutDone, never>, never, Env>, Pull.Pull<OutElem, OutErr, OutDone, never>, [upstream: Pull.Pull<InElem, InErr, InDone, never>, scope: Scope.Scope, forkedScope: Scope.Scope]>(body: (this: Types.unassigned, upstream: Pull.Pull<InElem, InErr, InDone, never>, scope: Scope.Scope, forkedScope: Scope.Scope) => Generator<...>) => (upstream: Pull.Pull<...>, scope: Scope.Scope, forkedScope: Scope.Scope) => Effect.Effect<...> (+41 overloads)fnUntraced(function*(upstream: Pull.Pull<InElem, InErr, InDone, never>(parameter) upstream: {
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;
}
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
forkedScope: Scope.Scope(parameter) forkedScope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
let option: Option.Option<A>option = import OptionOption.const none: <A = never>() => Option<A>Creates an Option representing the absence of a value.
When to use
Use to represent a missing or uninitialized value, such as returning "no
result" from a function.
Details
- Returns
Option<never>, which is a subtype of Option<A> for any A
- Always returns the same singleton instance
Example (Creating an empty Option)
import { Option } from "effect"
// ┌─── Option<never>
// ▼
const noValue = Option.none()
console.log(noValue)
// Output: { _id: 'Option', _tag: 'None' }
none<function (type parameter) A in <A, E, R, OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(acquire: Effect.Effect<A, E, R>, use: (a: A) => Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, release: (a: A, exit: Exit.Exit<OutDone, OutErr>) => Effect.Effect<unknown>): Channel<OutElem, OutErr | E, OutDone, InElem, InErr, InDone, Env | R>A>()
yield* import ScopeScope.const addFinalizerExit: (
scope: Scope,
finalizer: (
exit: Exit<any, any>
) => Effect<unknown>
) => Effect<void>
Registers an exit-aware finalizer on a scope.
When to use
Use when cleanup needs to know whether the scope closed with success,
failure, or interruption.
Details
If the scope is open, the finalizer runs when the scope closes and receives
the scope's exit value. If the scope is already closed, the finalizer runs
immediately with the stored exit value.
Example (Adding an exit-aware finalizer)
import { Console, Effect, Exit, Scope } from "effect"
const withResource = Effect.gen(function*() {
const scope = yield* Scope.make()
// Add a finalizer for cleanup
yield* Scope.addFinalizerExit(
scope,
(exit) =>
Console.log(
`Cleaning up resource. Exit: ${
Exit.isSuccess(exit) ? "Success" : "Failure"
}`
)
)
// Use the resource
yield* Console.log("Using resource")
// Close the scope
yield* Scope.close(scope, Exit.void)
})
addFinalizerExit(forkedScope: Scope.Scope(parameter) forkedScope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
exit: Exit.Exit<any, any>exit) =>
import OptionOption.const isSome: <A>(
self: Option<A>
) => self is Some<A>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(let option: Option.Option<A>option)
? release: (
a: A,
exit: Exit.Exit<OutDone, OutErr>
) => Effect.Effect<unknown>
let option: Option.Some<A>let option: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
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;
}
Some<A>.value: Avalue, exit: Exit.Exit<any, any>exit as any)
: import EffectEffect.const void: Effect.Effect<void, never, never>(alias) const void: {
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;
}
Returns an effect that succeeds with void.
void)
const const value: Avalue = yield* import EffectEffect.const uninterruptible: <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E, R>
Returns a new effect that disables interruption for the given effect.
Example (Preventing interruption)
import { Console, Effect, Fiber } from "effect"
const criticalTask = Effect.gen(function*() {
yield* Console.log("Starting critical section...")
yield* Effect.sleep("2 seconds")
yield* Console.log("Critical section completed")
})
const program = Effect.uninterruptible(criticalTask)
const fiber = Effect.runFork(program)
// Even if interrupted, the critical task will complete
Effect.runPromise(Fiber.interrupt(fiber))
uninterruptible(acquire: Effect.Effect<A, E, R>(parameter) acquire: {
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;
}
let option: Option.Option<A>option = import OptionOption.const some: <A>(value: A) => Option<A>Wraps the given value into an Option to represent its presence.
When to use
Use to wrap a known present value as Option
- Returning a successful result from a partial function
Details
- Always returns
Some<A>
- Does not filter
null or undefined; use
fromNullishOr
for that
Example (Wrapping a value)
import { Option } from "effect"
// ┌─── Option<number>
// ▼
const value = Option.some(1)
console.log(value)
// Output: { _id: 'Option', _tag: 'Some', value: 1 }
some(const value: Avalue)
return yield* const toTransform: <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
channel: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => (
upstream: Pull.Pull<InElem, InErr, InDone>,
scope: Scope.Scope
) => Effect.Effect<
Pull.Pull<OutElem, OutErr, OutDone>,
never,
Env
>
Converts a Channel back to its underlying transformation function.
Example (Extracting channel transforms)
import { Channel } from "effect"
const channel = Channel.succeed(42)
const transform = Channel.toTransform(channel)
// transform can now be used directly
toTransform(use: (
a: A
) => Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
const value: Avalue))(upstream: Pull.Pull<InElem, InErr, InDone, never>(parameter) upstream: {
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;
}
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}