<OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <
OutErr,
OutDone,
Env
>(
self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>
) => Effect.Effect<OutDone, OutErr | EX, Env | RX>
<OutElem, OutErr, OutDone, Env, EX, RX>(
self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>,
f: (o: OutElem) => Effect.Effect<void, EX, RX>
): Effect.Effect<OutDone, OutErr | EX, Env | RX>Runs a channel and applies an effect to each output element.
Example (Running effects for each output)
import { Channel, Console, Data } from "effect"
class ForEachError extends Data.TaggedError("ForEachError")<{
readonly element: unknown
}> {}
// Create a channel with numbers
const numbersChannel = Channel.fromIterable([1, 2, 3])
// Run forEach to log each element
const forEachEffect = Channel.runForEach(
numbersChannel,
(n) => Console.log(`Processing: ${n}`)
)
// Logs: "Processing: 1", "Processing: 2", "Processing: 3"export const const runForEach: {
<OutElem, EX, RX>(
f: (o: OutElem) => Effect.Effect<void, EX, RX>
): <OutErr, OutDone, Env>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
) => Effect.Effect<
OutDone,
OutErr | EX,
Env | RX
>
<OutElem, OutErr, OutDone, Env, EX, RX>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>,
f: (o: OutElem) => Effect.Effect<void, EX, RX>
): Effect.Effect<OutDone, OutErr | EX, Env | RX>
}
Runs a channel and applies an effect to each output element.
Example (Running effects for each output)
import { Channel, Console, Data } from "effect"
class ForEachError extends Data.TaggedError("ForEachError")<{
readonly element: unknown
}> {}
// Create a channel with numbers
const numbersChannel = Channel.fromIterable([1, 2, 3])
// Run forEach to log each element
const forEachEffect = Channel.runForEach(
numbersChannel,
(n) => Console.log(`Processing: ${n}`)
)
// Logs: "Processing: 1", "Processing: 2", "Processing: 3"
runForEach: {
<function (type parameter) OutElem in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem, function (type parameter) EX in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) RX in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>(
f: (
o: OutElem
) => Effect.Effect<void, EX, RX>
o: OutElemo: function (type parameter) OutElem in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem) => 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<void, function (type parameter) EX in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) RX in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>
): <function (type parameter) OutErr in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr, function (type parameter) OutDone in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, function (type parameter) Env in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
(parameter) self: {
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 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 <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem, function (type parameter) OutErr in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr, function (type parameter) OutDone in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, unknown, unknown, unknown, function (type parameter) Env in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env>
) => 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) OutDone in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, function (type parameter) OutErr in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr | function (type parameter) EX in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) Env in <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env | function (type parameter) RX in <OutElem, EX, RX>(f: (o: OutElem) => Effect.Effect<void, EX, RX>): <OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, function (type parameter) Env in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env, function (type parameter) EX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) RX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
(parameter) self: {
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 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 <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, unknown, unknown, unknown, function (type parameter) Env in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env>,
f: (
o: OutElem
) => Effect.Effect<void, EX, RX>
o: OutElemo: function (type parameter) OutElem in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem) => 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<void, function (type parameter) EX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) RX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>
): 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) OutDone in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr | function (type parameter) EX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) Env in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env | function (type parameter) RX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>
} = dual<(...args: Array<any>) => any, <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>>(arity: 2, body: <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>): ((...args: Array<any>) => any) & (<OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>) => Effect.Effect<OutDone, OutErr | EX, Env | RX>) (+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(
2,
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, function (type parameter) Env in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env, function (type parameter) EX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) RX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
(parameter) self: {
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 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 <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, unknown, unknown, unknown, function (type parameter) Env in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env>,
f: (
o: OutElem
) => Effect.Effect<void, EX, RX>
o: OutElemo: function (type parameter) OutElem in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutElem) => 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<void, function (type parameter) EX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) RX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>RX>
): 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) OutDone in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutDone, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>OutErr | function (type parameter) EX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>EX, function (type parameter) Env in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>Env | function (type parameter) RX in <OutElem, OutErr, OutDone, Env, EX, RX>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>, f: (o: OutElem) => Effect.Effect<void, EX, RX>): Effect.Effect<OutDone, OutErr | EX, Env | RX>RX> =>
const runWith: <
OutElem,
OutErr,
OutDone,
Env,
EX,
RX,
AH = OutDone,
EH = never,
RH = never
>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>,
f: (
pull: Pull.Pull<OutElem, OutErr, OutDone>
) => Effect.Effect<void, EX, RX>,
onHalt?: (
leftover: OutDone
) => Effect.Effect<AH, EH, RH>
) => Effect.Effect<
AH,
Pull.ExcludeDone<EX> | EH,
Env | RX | RH
>
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
(parameter) self: {
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; <…;
}
pull: Pull.Pull<
OutElem,
OutErr,
OutDone,
never
>
(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.const forever: <
Arg extends
| Effect<any, any, any>
| {
readonly disableYield?:
| boolean
| undefined
}
| undefined = {
readonly disableYield?: boolean | undefined
}
>(
effectOrOptions?: Arg,
options?:
| {
readonly disableYield?:
| boolean
| undefined
}
| undefined
) => [Arg] extends [
Effect<infer _A, infer _E, infer _R>
]
? Effect<never, _E, _R>
: <A, E, R>(
self: Effect<A, E, R>
) => Effect<never, E, R>
Repeats this effect forever (until the first error).
Example (Repeating forever)
import { Console, Effect, Fiber } from "effect"
const task = Effect.gen(function*() {
yield* Console.log("Task running...")
yield* Effect.sleep("1 second")
})
// This will run forever, printing every second
const program = task.pipe(Effect.forever)
// This will run forever, without yielding every iteration
const programNoYield = task.pipe(Effect.forever({ disableYield: true }))
// Run for 5 seconds then interrupt
const timedProgram = Effect.gen(function*() {
const fiber = yield* Effect.forkChild(program)
yield* Effect.sleep("5 seconds")
yield* Fiber.interrupt(fiber)
})
forever(import EffectEffect.const flatMap: {
<A, B, E1, R1>(
f: (a: A) => Effect<B, E1, R1>
): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E1 | E, R1 | R>
<A, E, R, B, E1, R1>(
self: Effect<A, E, R>,
f: (a: A) => Effect<B, E1, R1>
): Effect<B, E | E1, R | R1>
}
pull: Pull.Pull<
OutElem,
OutErr,
OutDone,
never
>
(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;
}
f: (
o: OutElem
) => Effect.Effect<void, EX, RX>
disableYield?: boolean | undefineddisableYield: true }))
)