<OutElem, X, OutErr1, Env1>(
f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>,
options?: { readonly concurrency?: number | "unbounded" | undefined }
): <OutErr, OutDone, InElem, InErr, InDone, Env>(
self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>
) => Channel<
OutElem,
OutErr1 | OutErr,
OutDone,
InElem,
InErr,
InDone,
Env1 | Env
>
<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(
self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>,
options?: { readonly concurrency?: number | "unbounded" | undefined }
): Channel<
OutElem,
OutErr | OutErr1,
OutDone,
InElem,
InErr,
InDone,
Env | Env1
>Applies a side effect function to each output element of the channel, returning a new channel that emits the same elements.
Details
The tap function allows you to perform side effects (like logging or
debugging) on each element emitted by a channel without modifying the
elements themselves.
Example (Tapping channel output)
import { Channel, Console, Data } from "effect"
class LogError extends Data.TaggedError("LogError")<{
readonly message: string
}> {}
// Create a channel that outputs numbers
const numberChannel = Channel.fromIterable([1, 2, 3])
// Tap into each output element to perform side effects
const tappedChannel = Channel.tap(
numberChannel,
(n) => Console.log(`Processing number: ${n}`)
)
// The channel still outputs the same elements but logs each one
// Outputs: 1, 2, 3 (while logging each)sequencing
Source effect/Channel.ts:215027 lines
export const const tap: {
<OutElem, X, OutErr1, Env1>(
f: (
d: Types.NoInfer<OutElem>
) => Effect.Effect<X, OutErr1, Env1>,
options?: {
readonly concurrency?:
| number
| "unbounded"
| undefined
}
): <
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem,
OutErr1 | OutErr,
OutDone,
InElem,
InErr,
InDone,
Env1 | Env
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
X,
OutErr1,
Env1
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
f: (
d: Types.NoInfer<OutElem>
) => Effect.Effect<X, OutErr1, Env1>,
options?: {
readonly concurrency?:
| number
| "unbounded"
| undefined
}
): Channel<
OutElem,
OutErr | OutErr1,
OutDone,
InElem,
InErr,
InDone,
Env | Env1
>
}
Applies a side effect function to each output element of the channel,
returning a new channel that emits the same elements.
Details
The tap function allows you to perform side effects (like logging or
debugging) on each element emitted by a channel without modifying the
elements themselves.
Example (Tapping channel output)
import { Channel, Console, Data } from "effect"
class LogError extends Data.TaggedError("LogError")<{
readonly message: string
}> {}
// Create a channel that outputs numbers
const numberChannel = Channel.fromIterable([1, 2, 3])
// Tap into each output element to perform side effects
const tappedChannel = Channel.tap(
numberChannel,
(n) => Console.log(`Processing number: ${n}`)
)
// The channel still outputs the same elements but logs each one
// Outputs: 1, 2, 3 (while logging each)
tap: {
<function (type parameter) OutElem in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) X in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) OutErr1 in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) Env1 in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
f: (
d: Types.NoInfer<OutElem>
) => Effect.Effect<X, OutErr1, Env1>
d: Types.NoInfer<OutElem>d: import TypesTypes.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) OutElem in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | 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) X in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) OutErr1 in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) Env1 in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
}
| undefined
concurrency?: number | "unbounded" | undefinedconcurrency?: number | "unbounded" | undefined
}
): <function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>Env>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>Env>
) => 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, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) OutErr1 in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>InDone, function (type parameter) Env1 in <OutElem, X, OutErr1, Env1>(f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>
function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem, OutErr1 | OutErr, OutDone, InElem, InErr, InDone, Env1 | Env>Env>
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) X in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
f: (
d: Types.NoInfer<OutElem>
) => Effect.Effect<X, OutErr1, Env1>
d: Types.NoInfer<OutElem>d: import TypesTypes.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) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
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) X in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
}
| undefined
concurrency?: number | "unbounded" | undefinedconcurrency?: number | "unbounded" | undefined
}
): 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, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
dual<(...args: Array<any>) => any, <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}) => Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>>(isDataFirst: (args: IArguments) => boolean, body: <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}) => Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>): ((...args: Array<any>) => any) & (<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}) => Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>) (+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 isChannel: (
u: unknown
) => u is Channel<
unknown,
unknown,
unknown,
unknown,
unknown,
unknown,
unknown
>
Checks whether a value is a Channel.
Example (Checking for channels)
import { Channel } from "effect"
const channel = Channel.succeed(42)
console.log(Channel.isChannel(channel)) // true
console.log(Channel.isChannel("not a channel")) // false
isChannel(args: IArgumentsargs[0]),
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) X in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
f: (
d: Types.NoInfer<OutElem>
) => Effect.Effect<X, OutErr1, Env1>
d: Types.NoInfer<OutElem>d: import TypesTypes.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) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
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) X in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
}
| undefined
concurrency?: number | "unbounded" | undefinedconcurrency?: number | "unbounded" | undefined
}
): 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, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, X, OutErr1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Types.NoInfer<OutElem>) => Effect.Effect<X, OutErr1, Env1>, options?: {
readonly concurrency?: number | "unbounded" | undefined;
}): Channel<OutElem, OutErr | OutErr1, OutDone, InElem, InErr, InDone, Env | Env1>
const mapEffect: {
<OutElem, OutElem1, OutErr1, Env1>(
f: (
d: OutElem,
i: number
) => Effect.Effect<OutElem1, OutErr1, Env1>,
options?: {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | undefined
}
): <
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem1,
OutErr1 | OutErr,
OutDone,
InElem,
InErr,
InDone,
Env1 | Env
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem1,
OutErr1,
Env1
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
f: (
d: OutElem,
i: number
) => Effect.Effect<OutElem1, OutErr1, Env1>,
options?: {
readonly concurrency?:
| number
| "unbounded"
| undefined
readonly unordered?: boolean | undefined
}
): Channel<
OutElem1,
OutErr | OutErr1,
OutDone,
InElem,
InErr,
InDone,
Env | Env1
>
}
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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; <…;
}
a: OutElema) => import EffectEffect.const as: {
<B>(value: B): <A, E, R>(
self: Effect<A, E, R>
) => Effect<B, E, R>
<A, E, R, B>(
self: Effect<A, E, R>,
value: B
): Effect<B, E, R>
}
f: (
d: Types.NoInfer<OutElem>
) => Effect.Effect<X, OutErr1, Env1>
a: OutElema), a: OutElema), options: | {
readonly concurrency?:
| number
| "unbounded"
| undefined
}
| undefined