<A2, E2, R2>(options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
<A, E, R, A2, E2, R2>(
self: Effect<A, E, R>,
options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>
}
): Effect<A | A2, E | E2, R | R2>Applies a timeout to an effect, with a fallback effect executed if the timeout is reached.
When to use
Use when a timeout of an Effect should switch to a fallback effect.
Details
The fallback effect is created lazily by orElse and may introduce its own
success, failure, and requirement types.
Gotchas
If the timeout wins, the source effect is interrupted before the fallback is run.
Example (Falling back on timeout)
import { Console, Effect } from "effect"
const slowQuery = Effect.gen(function*() {
yield* Console.log("Starting database query...")
yield* Effect.sleep("5 seconds")
return "Database result"
})
// Use cached data as fallback when timeout is reached
const program = Effect.timeoutOrElse(slowQuery, {
duration: "2 seconds",
orElse: () =>
Effect.gen(function*() {
yield* Console.log("Query timed out, using cached data")
return "Cached result"
})
})
Effect.runPromise(program).then(console.log)
// Output:
// Starting database query...
// Query timed out, using cached data
// Cached resultexport const const timeoutOrElse: {
<A2, E2, R2>(options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>
}): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A | A2, E | E2, R | R2>
<A, E, R, A2, E2, R2>(
self: Effect<A, E, R>,
options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>
}
): Effect<A | A2, E | E2, R | R2>
}
Applies a timeout to an effect, with a fallback effect executed if the timeout is reached.
When to use
Use when a timeout of an Effect should switch to a fallback effect.
Details
The fallback effect is created lazily by orElse and may introduce its own
success, failure, and requirement types.
Gotchas
If the timeout wins, the source effect is interrupted before the fallback is
run.
Example (Falling back on timeout)
import { Console, Effect } from "effect"
const slowQuery = Effect.gen(function*() {
yield* Console.log("Starting database query...")
yield* Effect.sleep("5 seconds")
return "Database result"
})
// Use cached data as fallback when timeout is reached
const program = Effect.timeoutOrElse(slowQuery, {
duration: "2 seconds",
orElse: () =>
Effect.gen(function*() {
yield* Console.log("Query timed out, using cached data")
return "Cached result"
})
})
Effect.runPromise(program).then(console.log)
// Output:
// Starting database query...
// Query timed out, using cached data
// Cached result
timeoutOrElse: {
<function (type parameter) A2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) E2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) R2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>
}
duration: Duration.Inputduration: import DurationDuration.type Input =
| number
| bigint
| Duration.Duration
| readonly [seconds: number, nanos: number]
| `${number} nano`
| `${number} nanos`
| `${number} micro`
| `${number} micros`
| `${number} milli`
| `${number} millis`
| `${number} second`
| `${number} seconds`
| `${number} minute`
| `${number} minutes`
| `${number} hour`
| `${number} hours`
| `${number} day`
| `${number} days`
| `${number} week`
| `${number} weeks`
| "Infinity"
| "-Infinity"
| Duration.DurationObject
Valid input types that can be converted to a Duration.
When to use
Use when an API should accept any value that Effect can convert into a
Duration, including existing durations, millisecond numbers, nanosecond
bigints, high-resolution tuples, duration strings, infinity strings, or
duration objects.
Details
String inputs accept values like "10 seconds", "500 millis",
"Infinity", and "-Infinity". Finite fractional values that are
normalized to nanoseconds are rounded to the nearest nanosecond, with ties
away from zero.
Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>orElse: type LazyArg<A> = () => AA zero-argument function that produces a value when invoked.
When to use
Use to type a lazy value provider that should not run until called.
Example (Creating a lazy argument)
import { Function } from "effect"
const constNull: Function.LazyArg<null> = Function.constant(null)
LazyArg<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) A2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) E2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) R2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>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<A | A2, E | E2, R | R2>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>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) A in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>A | function (type parameter) A2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>E | function (type parameter) E2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A | A2, E | E2, R | R2>R | function (type parameter) R2 in <A2, E2, R2>(options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>
function (type parameter) A in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
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, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>
}
duration: Duration.Inputduration: import DurationDuration.type Input =
| number
| bigint
| Duration.Duration
| readonly [seconds: number, nanos: number]
| `${number} nano`
| `${number} nanos`
| `${number} micro`
| `${number} micros`
| `${number} milli`
| `${number} millis`
| `${number} second`
| `${number} seconds`
| `${number} minute`
| `${number} minutes`
| `${number} hour`
| `${number} hours`
| `${number} day`
| `${number} days`
| `${number} week`
| `${number} weeks`
| "Infinity"
| "-Infinity"
| Duration.DurationObject
Valid input types that can be converted to a Duration.
When to use
Use when an API should accept any value that Effect can convert into a
Duration, including existing durations, millisecond numbers, nanosecond
bigints, high-resolution tuples, duration strings, infinity strings, or
duration objects.
Details
String inputs accept values like "10 seconds", "500 millis",
"Infinity", and "-Infinity". Finite fractional values that are
normalized to nanoseconds are rounded to the nearest nanosecond, with ties
away from zero.
Input
readonly orElse: LazyArg<Effect<A2, E2, R2>>orElse: type LazyArg<A> = () => AA zero-argument function that produces a value when invoked.
When to use
Use to type a lazy value provider that should not run until called.
Example (Creating a lazy argument)
import { Function } from "effect"
const constNull: Function.LazyArg<null> = Function.constant(null)
LazyArg<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) A2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
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, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) A2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) E in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) E2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) R in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
function (type parameter) R2 in <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: {
readonly duration: Duration.Input;
readonly orElse: LazyArg<Effect<A2, E2, R2>>;
}): Effect<A | A2, E | E2, R | R2>
import internalinternal.const timeoutOrElse: {
<A2, E2, R2>(options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<
Effect.Effect<A2, E2, R2>
>
}): <A, E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<A | A2, E | E2, R | R2>
<A, E, R, A2, E2, R2>(
self: Effect.Effect<A, E, R>,
options: {
readonly duration: Duration.Input
readonly orElse: LazyArg<
Effect.Effect<A2, E2, R2>
>
}
): Effect.Effect<A | A2, E | E2, R | R2>
}