<E>(evaluate: LazyArg<Cause.Cause<E>>): Effect<never, E>Creates an Effect that represents a failure with a Cause computed lazily.
When to use
Use to defer computing a full Cause until the effect is run.
Details
The cause-producing function is evaluated each time the effect is executed.
Example (Lazily creating a Cause)
import { Cause, Effect } from "effect"
const program = Effect.failCauseSync(() =>
Cause.fail("Error computed at runtime")
)
Effect.runPromiseExit(program).then(console.log)
// Output: { _id: 'Exit', _tag: 'Failure', cause: ... }export const const failCauseSync: <E>(
evaluate: LazyArg<Cause.Cause<E>>
) => Effect<never, E>
Creates an Effect that represents a failure with a Cause computed lazily.
When to use
Use to defer computing a full Cause until the effect is run.
Details
The cause-producing function is evaluated each time the effect is executed.
Example (Lazily creating a Cause)
import { Cause, Effect } from "effect"
const program = Effect.failCauseSync(() =>
Cause.fail("Error computed at runtime")
)
Effect.runPromiseExit(program).then(console.log)
// Output: { _id: 'Exit', _tag: 'Failure', cause: ... }
failCauseSync: <function (type parameter) E in <E>(evaluate: LazyArg<Cause.Cause<E>>): Effect<never, E>E>(
evaluate: LazyArg<Cause.Cause<E>>evaluate: 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<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 <E>(evaluate: LazyArg<Cause.Cause<E>>): Effect<never, E>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<never, function (type parameter) E in <E>(evaluate: LazyArg<Cause.Cause<E>>): Effect<never, E>E> = import internalinternal.const failCauseSync: <E>(
evaluate: LazyArg<Cause.Cause<E>>
) => Effect.Effect<never, E>