<SO, OutElem, SE, SR>(
schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>
): <OutErr, OutDone, InElem, InErr, InDone, Env>(
self: Channel<
OutElem,
OutErr | SE,
OutDone,
InElem,
InErr,
InDone,
Env | SR
>
) => Channel<
OutElem,
OutErr | SE,
OutDone | SO,
InElem,
InErr,
InDone,
Env | SR
>
<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(
self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
schedule: Schedule.Schedule<SO, OutElem, SE, SR>
): Channel<
OutElem,
OutErr | SE,
OutDone | SO,
InElem,
InErr,
InDone,
Env | SR
>Runs a schedule step for each output element while preserving the emitted elements.
Details
The schedule receives each output element as input. Schedule delays are applied between emitted elements. If the schedule fails, the returned channel fails. If the schedule finishes, the returned channel completes with the schedule output.
sequencing
Source effect/Channel.ts:310530 lines
export const const schedule: {
<SO, OutElem, SE, SR>(
schedule: Schedule.Schedule<
SO,
Types.NoInfer<OutElem>,
SE,
SR
>
): <
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr | SE,
OutDone,
InElem,
InErr,
InDone,
Env | SR
>
) => Channel<
OutElem,
OutErr | SE,
OutDone | SO,
InElem,
InErr,
InDone,
Env | SR
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
SO,
SE,
SR
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
schedule: Schedule.Schedule<
SO,
OutElem,
SE,
SR
>
): Channel<
OutElem,
OutErr | SE,
OutDone | SO,
InElem,
InErr,
InDone,
Env | SR
>
}
Runs a schedule step for each output element while preserving the emitted
elements.
Details
The schedule receives each output element as input. Schedule delays are
applied between emitted elements. If the schedule fails, the returned channel
fails. If the schedule finishes, the returned channel completes with the
schedule output.
schedule: {
<function (type parameter) SO in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) OutElem in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) SE in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) SR in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>(
schedule: Schedule.Schedule<
SO,
Types.NoInfer<OutElem>,
SE,
SR
>
(parameter) schedule: {
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; <…;
}
import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, 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 <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem>, function (type parameter) SE in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) SR in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>
): <function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env>(
self: Channel<
OutElem,
OutErr | SE,
OutDone,
InElem,
InErr,
InDone,
Env | SR
>
(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 <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr | function (type parameter) SE in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env | function (type parameter) SR in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>
) => 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 <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr | function (type parameter) SE in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone | function (type parameter) SO in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env | function (type parameter) SR in <SO, OutElem, SE, SR>(schedule: Schedule.Schedule<SO, Types.NoInfer<OutElem>, SE, SR>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr | SE, OutDone, InElem, InErr, InDone, Env | SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env, function (type parameter) SO in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) SE in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) SR in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>(
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, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env>,
schedule: Schedule.Schedule<SO, OutElem, SE, SR>(parameter) schedule: {
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; <…;
}
import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) SE in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) SR in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>
): 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, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr | function (type parameter) SE in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone | function (type parameter) SO in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env | function (type parameter) SR in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>
} = dual<(...args: Array<any>) => any, <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>>(arity: 2, body: <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>): ((...args: Array<any>) => any) & (<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>) => Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>) (+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, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env, function (type parameter) SO in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) SE in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) SR in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>(
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, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env>,
schedule: Schedule.Schedule<SO, OutElem, SE, SR>(parameter) schedule: {
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; <…;
}
import ScheduleSchedule.interface Schedule<out Output, in Input = unknown, out Error = never, out Env = never>A Schedule defines a strategy for repeating or retrying effects based on some policy.
Example (Defining retry and repeat schedules)
import { Console, Data, Effect, Schedule } from "effect"
class NetworkError extends Data.TaggedError("NetworkError")<{
readonly attempt: number
}> {}
// Basic retry schedule - retry up to 3 times with exponential backoff
const retrySchedule = Schedule.max([
Schedule.exponential("100 millis"),
Schedule.recurs(3)
])
// Basic repeat schedule - repeat every 30 seconds forever
const repeatSchedule: Schedule.Schedule<number, unknown, never> = Schedule
.spaced("30 seconds")
const program = Effect.gen(function*() {
let attempts = 0
const result1 = yield* Effect.retry(
Effect.gen(function*() {
attempts++
if (attempts < 3) {
return yield* Effect.fail(new NetworkError({ attempt: attempts }))
}
return "Success"
}),
retrySchedule
)
console.log(result1) // "Success"
yield* Console.log("heartbeat").pipe(
Effect.repeat(repeatSchedule.pipe(Schedule.upTo({ times: 5 })))
)
})
The Schedule namespace contains types and utilities for working with schedules.
Schedule<function (type parameter) SO in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) SE in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) SR in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR>
): 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, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr | function (type parameter) SE in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone | function (type parameter) SO in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>Env | function (type parameter) SR in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR> =>
const transformPull: <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem2,
OutErr2,
OutDone2,
Env2,
OutErrX,
EnvX
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
f: (
pull: Pull.Pull<OutElem, OutErr, OutDone>,
scope: Scope.Scope
) => Effect.Effect<
Pull.Pull<OutElem2, OutErr2, OutDone2, Env2>,
OutErrX,
EnvX
>
) => Channel<
OutElem2,
Pull.ExcludeDone<OutErr2> | OutErrX,
OutDone2,
InElem,
InErr,
InDone,
Env | Env2 | EnvX
>
Transforms a Channel by applying a function to its Pull implementation.
Example (Transforming pull behavior)
import { Channel, Effect } from "effect"
// Transform a channel by modifying its pull behavior
const originalChannel = Channel.fromIterable([1, 2, 3])
const transformedChannel = Channel.transformPull(
originalChannel,
(pull, scope) =>
Effect.succeed(
Effect.map(pull, (value) => value * 2)
)
)
// Outputs: 2, 4, 6
transformPull(
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; <…;
}
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;
}
_scope: Scope.Scope(parameter) _scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import EffectEffect.const map: {
<A, B>(f: (a: A) => B): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E, R>
<A, E, R, B>(
self: Effect<A, E, R>,
f: (a: A) => B
): Effect<B, E, R>
}
import ScheduleSchedule.const toStepWithSleep: <
Output,
Input,
Error,
Env
>(
schedule: Schedule<Output, Input, Error, Env>
) => Effect<
(
input: Input
) => Pull.Pull<Output, Error, Output, Env>,
never,
Env
>
Extracts a step function from a Schedule that automatically handles sleep delays.
Example (Extracting a sleeping step function)
import { Effect, Schedule } from "effect"
// Convert schedule to step function with automatic sleeping
const schedule = Schedule.spaced("1 second").pipe(Schedule.upTo({ times: 3 }))
const program = Effect.gen(function*() {
const stepWithSleep = yield* Schedule.toStepWithSleep(schedule)
// Each call will automatically sleep for the scheduled delay
console.log("Starting...")
const result1 = yield* stepWithSleep("first")
console.log(`First result: ${result1}`)
const result2 = yield* stepWithSleep("second")
console.log(`Second result: ${result2}`)
const result3 = yield* stepWithSleep("third")
console.log(`Third result: ${result3}`)
})
toStepWithSleep(schedule: Schedule.Schedule<SO, OutElem, SE, SR>(parameter) schedule: {
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; <…;
}
step: (
input: OutElem
) => Pull.Pull<SO, SE, SO, SR>
const pullWithStep: Pull.Pull<
OutElem,
OutErr | SE,
OutDone | SO,
SR
>
const pullWithStep: {
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 PullPull.interface Pull<out A, out E = never, out Done = void, out R = never>An effectful pull step that either produces a value, fails with E, or
signals completion with Cause.Done<Done>.
When to use
Use to model one low-level pull step when a consumer repeatedly evaluates an
effect that may emit a value, fail normally, or signal normal completion
through Cause.Done.
Details
Pull represents completion in the error channel so low-level stream
consumers can distinguish ordinary failures from end-of-input and carry a
leftover value when needed.
Pull<
function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutElem,
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutErr | function (type parameter) SE in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SE,
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>OutDone | function (type parameter) SO in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SO,
function (type parameter) SR in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, SO, SE, SR>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, schedule: Schedule.Schedule<SO, OutElem, SE, SR>): Channel<OutElem, OutErr | SE, OutDone | SO, InElem, InErr, InDone, Env | SR>SR
> = import EffectEffect.const tap: {
<A, B, E2, R2>(
f: (a: NoInfer<A>) => Effect<B, E2, R2>
): <E, R>(
self: Effect<A, E, R>
) => Effect<A, E | E2, R | R2>
<B, E2, R2>(f: Effect<B, E2, R2>): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect<A, E, R>,
f: (a: NoInfer<A>) => Effect<B, E2, R2>
): Effect<A, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect<A, E, R>,
f: Effect<B, E2, R2>
): Effect<A, E | E2, R | R2>
}
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;
}
step: (
input: OutElem
) => Pull.Pull<SO, SE, SO, SR>
const pullWithStep: Pull.Pull<
OutElem,
OutErr | SE,
OutDone | SO,
SR
>
const pullWithStep: {
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;
}
Referenced by 1 symbols