<E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <
A,
R
>(
self: Effect<A, E, R>
) => Effect<A, E, R2 | R>
<A, E, R, X, R2>(
self: Effect<A, E, R>,
cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>
): Effect<A, E, R2 | R>Runs the specified effect if this effect fails, providing the error to the effect if it exists. The provided effect will not be interrupted.
Example (Running cleanup on failure)
import { Cause, Console, Data, Effect } from "effect"
class TaskError extends Data.TaggedError("TaskError")<{ readonly message: string }> {}
const task = Effect.fail(new TaskError({ message: "Something went wrong" }))
const program = Effect.onError(
task,
(cause) => Console.log(`Cleanup on error: ${Cause.squash(cause)}`)
)
Effect.runPromise(program).catch(console.error)
// Output:
// Cleanup on error: TaskError: Something went wrong
// TaskError: Something went wrongexport const const onError: {
<E, X, R2>(
cleanup: (
cause: Cause.Cause<E>
) => Effect<X, never, R2>
): <A, R>(
self: Effect<A, E, R>
) => Effect<A, E, R2 | R>
<A, E, R, X, R2>(
self: Effect<A, E, R>,
cleanup: (
cause: Cause.Cause<E>
) => Effect<X, never, R2>
): Effect<A, E, R2 | R>
}
Runs the specified effect if this effect fails, providing the error to the
effect if it exists. The provided effect will not be interrupted.
Example (Running cleanup on failure)
import { Cause, Console, Data, Effect } from "effect"
class TaskError extends Data.TaggedError("TaskError")<{ readonly message: string }> {}
const task = Effect.fail(new TaskError({ message: "Something went wrong" }))
const program = Effect.onError(
task,
(cause) => Console.log(`Cleanup on error: ${Cause.squash(cause)}`)
)
Effect.runPromise(program).catch(console.error)
// Output:
// Cleanup on error: TaskError: Something went wrong
// TaskError: Something went wrong
onError: {
<function (type parameter) E in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>E, function (type parameter) X in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>X, function (type parameter) R2 in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>R2>(
cleanup: (
cause: Cause.Cause<E>
) => Effect<X, never, R2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.type Cause.Cause = /*unresolved*/ anyCause<function (type parameter) E in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>E>) => interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) X in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>X, never, function (type parameter) R2 in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>R2>
): <function (type parameter) A in <A, R>(self: Effect<A, E, R>): Effect<A, E, R2 | R>A, function (type parameter) R in <A, R>(self: Effect<A, E, R>): Effect<A, E, R2 | R>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, R>(self: Effect<A, E, R>): Effect<A, E, R2 | R>A, function (type parameter) E in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>E, function (type parameter) R in <A, R>(self: Effect<A, E, R>): Effect<A, E, R2 | R>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, R>(self: Effect<A, E, R>): Effect<A, E, R2 | R>A, function (type parameter) E in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>E, function (type parameter) R2 in <E, X, R2>(cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): <A, R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>R2 | function (type parameter) R in <A, R>(self: Effect<A, E, R>): Effect<A, E, R2 | R>R>
<function (type parameter) A in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>A, function (type parameter) E in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>E, function (type parameter) R in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>R, function (type parameter) X in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>X, function (type parameter) R2 in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | 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, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>A, function (type parameter) E in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>E, function (type parameter) R in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>R>,
cleanup: (
cause: Cause.Cause<E>
) => Effect<X, never, R2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.type Cause.Cause = /*unresolved*/ anyCause<function (type parameter) E in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>E>) => interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) X in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>X, never, function (type parameter) R2 in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | 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, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>A, function (type parameter) E in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>E, function (type parameter) R2 in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>R2 | function (type parameter) R in <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (cause: Cause.Cause<E>) => Effect<X, never, R2>): Effect<A, E, R2 | R>R>
} = import internalinternal.const onError: {
<A, E, XE, XR>(
f: (
cause: Cause.Cause<NoInfer<E>>
) => Effect.Effect<void, XE, XR>
): <R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<A, E | XE, R | XR>
<A, E, R, XE, XR>(
self: Effect.Effect<A, E, R>,
f: (
cause: Cause.Cause<NoInfer<E>>
) => Effect.Effect<void, XE, XR>
): Effect.Effect<A, E | XE, R | XR>
}