<Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <
A,
E,
R
>(
self: Effect<A, E, R>
) => Effect<Output, E, R | Env>
<A, E, R, Output, Error, Env>(
self: Effect<A, E, R>,
schedule: Schedule<Output, unknown, Error, Env>
): Effect<Output, E, R | Env>Runs an effect repeatedly according to a schedule and returns the schedule's final output.
When to use
Use to rerun a successful effect according to a Schedule when the schedule
does not need a custom initial input.
Details
The schedule is first stepped with undefined. After each successful
execution, the effect's success value is fed to the schedule to decide
whether to run again. The returned effect fails if the effect or schedule
fails, and otherwise succeeds with the schedule output when the schedule
completes.
Example (Scheduling repeated execution)
import { Console, Effect, Schedule } from "effect"
const task = Effect.gen(function*() {
yield* Console.log("Task executing...")
return Math.random()
})
// Repeat 3 times with 1 second delay between executions
const program = Effect.schedule(
task,
Schedule.addDelay(Schedule.recurs(2), () => Effect.succeed("1 second"))
)
Effect.runPromise(program).then(console.log)
// Output:
// Task executing... (immediate)
// Task executing... (after 1 second)
// Task executing... (after 1 second)
// Returns the count from Schedule.recursexport const const schedule: {
<Output, Error, Env>(
schedule: Schedule<
Output,
unknown,
Error,
Env
>
): <A, E, R>(
self: Effect<A, E, R>
) => Effect<Output, E, R | Env>
<A, E, R, Output, Error, Env>(
self: Effect<A, E, R>,
schedule: Schedule<
Output,
unknown,
Error,
Env
>
): Effect<Output, E, R | Env>
}
Runs an effect repeatedly according to a schedule and returns the schedule's
final output.
When to use
Use to rerun a successful effect according to a Schedule when the schedule
does not need a custom initial input.
Details
The schedule is first stepped with undefined. After each successful
execution, the effect's success value is fed to the schedule to decide
whether to run again. The returned effect fails if the effect or schedule
fails, and otherwise succeeds with the schedule output when the schedule
completes.
Example (Scheduling repeated execution)
import { Console, Effect, Schedule } from "effect"
const task = Effect.gen(function*() {
yield* Console.log("Task executing...")
return Math.random()
})
// Repeat 3 times with 1 second delay between executions
const program = Effect.schedule(
task,
Schedule.addDelay(Schedule.recurs(2), () => Effect.succeed("1 second"))
)
Effect.runPromise(program).then(console.log)
// Output:
// Task executing... (immediate)
// Task executing... (after 1 second)
// Task executing... (after 1 second)
// Returns the count from Schedule.recurs
schedule: {
<function (type parameter) Output in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Output, function (type parameter) Error in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Error, function (type parameter) Env in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Env>(
schedule: Schedule<Output, unknown, Error, Env>(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; <…;
}
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) Output in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Output, unknown, function (type parameter) Error in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Error, function (type parameter) Env in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Env>
): <function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>R>(self: Effect<A, E, R>(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; <…;
toString: () => string;
toJSON: () => unknown;
}
interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>R>) => 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) Output in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Output, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<Output, E, R | Env>R | function (type parameter) Env in <Output, Error, Env>(schedule: Schedule<Output, unknown, Error, Env>): <A, E, R>(self: Effect<A, E, R>) => Effect<Output, E, R | Env>Env>
<function (type parameter) A in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>A, function (type parameter) E in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>R, function (type parameter) Output in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Output, function (type parameter) Error in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Error, function (type parameter) Env in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Env>(
self: Effect<A, E, R>(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; <…;
toString: () => string;
toJSON: () => unknown;
}
interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>A, function (type parameter) E in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>R>,
schedule: Schedule<Output, unknown, Error, Env>(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; <…;
}
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) Output in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Output, unknown, function (type parameter) Error in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Error, function (type parameter) Env in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Env>
): 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) Output in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Output, function (type parameter) E in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>R | function (type parameter) Env in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Env>
} = dual<(...args: Array<any>) => any, <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>) => Effect<Output, E, R | Env>>(arity: 2, body: <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>) => Effect<Output, E, R | Env>): ((...args: Array<any>) => any) & (<A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>) => Effect<Output, E, R | Env>) (+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) A in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>A, function (type parameter) E in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>R, function (type parameter) Output in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Output, function (type parameter) Error in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Error, function (type parameter) Env in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Env>(
self: Effect<A, E, R>(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; <…;
toString: () => string;
toJSON: () => unknown;
}
interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>A, function (type parameter) E in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>R>,
schedule: Schedule<Output, unknown, Error, Env>(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; <…;
}
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) Output in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Output, unknown, function (type parameter) Error in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Error, function (type parameter) Env in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Env>
): 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) Output in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Output, function (type parameter) E in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>E, function (type parameter) R in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>R | function (type parameter) Env in <A, E, R, Output, Error, Env>(self: Effect<A, E, R>, schedule: Schedule<Output, unknown, Error, Env>): Effect<Output, E, R | Env>Env> => const scheduleFrom: {
<Input, Output, Error, Env>(
initial: Input,
schedule: Schedule<Output, Input, Error, Env>
): <E, R>(
self: Effect<Input, E, R>
) => Effect<Output, E, R | Env>
<Input, E, R, Output, Error, Env>(
self: Effect<Input, E, R>,
initial: Input,
schedule: Schedule<Output, Input, Error, Env>
): Effect<Output, E, R | Env>
}
self: Effect<A, E, R>(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; <…;
toString: () => string;
toJSON: () => unknown;
}
var undefinedundefined, schedule: Schedule<Output, unknown, Error, Env>(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; <…;
}