Failure<A, E>A failed Exit containing a Cause.
When to use
Use when working with the failed branch of an Exit after narrowing with
isFailure. Access the cause via the cause property after
narrowing.
Details
The Cause<E> may contain typed errors, defects, or interruptions.
Example (Accessing the failure cause)
import { Exit } from "effect"
const failure = Exit.fail("something went wrong")
if (Exit.isFailure(failure)) {
console.log(failure._tag) // "Failure"
console.log(failure.cause) // Cause representing the error
}export interface interface Failure<out A, out E>A failed Exit containing a Cause.
When to use
Use when working with the failed branch of an Exit after narrowing with
isFailure
. Access the cause via the cause property after
narrowing.
Details
The Cause<E> may contain typed errors, defects, or interruptions.
Example (Accessing the failure cause)
import { Exit } from "effect"
const failure = Exit.fail("something went wrong")
if (Exit.isFailure(failure)) {
console.log(failure._tag) // "Failure"
console.log(failure.cause) // Cause representing the error
}
Failure<out function (type parameter) A in Failure<out A, out E>A, out function (type parameter) E in Failure<out A, out E>E> extends Exit.interface Exit<A, E = never>.Proto<out A, out E = never>Base interface shared by both Success and Failure.
When to use
Use to describe the common protocol implemented by every Exit value.
Details
Every Exit is also an Effect, so you can yield it in Effect.gen.
Proto<function (type parameter) A in Failure<out A, out E>A, function (type parameter) E in Failure<out A, out E>E> {
readonly Failure<out A, out E>._tag: "Failure"_tag: "Failure"
readonly Failure<out A, out E>.cause: Cause.Cause<E>(property) Failure<out A, out E>.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.interface Cause<out E>A structured representation of how an Effect failed.
When to use
Use to preserve the full structured failure information for an effect instead
of collapsing it to a single error value.
Details
Access the individual failure entries through the reasons array, then
narrow each entry with
isFailReason
,
isDieReason
, or
- Use
hasFails
/
hasDies
/
hasInterrupts
to test
for the presence of specific reason kinds without iterating.
- Use
findError
/
findDefect
to extract the first value
of a given kind.
- Use
combine
to merge two causes.
Cause implements Equal — two causes with the same reasons (by value)
compare as equal.
Example (Creating and inspecting a cause)
import { Cause } from "effect"
const cause = Cause.fail("Something went wrong")
console.log(cause.reasons.length) // 1
console.log(Cause.isFailReason(cause.reasons[0])) // true
Companion namespace for the Cause interface.
Cause<function (type parameter) E in Failure<out A, out E>E>
}