effect-io-ai

Package: effect
Module: Effect

Effect.option

Encapsulates the result of an effect in an Option.

Details

This function wraps the outcome of an effect in an Option type. If the original effect succeeds, the success value is wrapped in Option.some. If the effect fails, the failure is converted to Option.none.

This is particularly useful for scenarios where you want to represent the absence of a value explicitly, without causing the resulting effect to fail. The resulting effect has an error type of never, meaning it cannot fail directly. However, unrecoverable errors, also referred to as defects, are not captured and will still result in failure.

Example (Using Effect.option to Handle Errors)

import { Effect } from "effect"

const maybe1 = Effect.option(Effect.succeed(1))

Effect.runPromiseExit(maybe1).then(console.log)
// Output:
// {
//   _id: 'Exit',
//   _tag: 'Success',
//   value: { _id: 'Option', _tag: 'Some', value: 1 }
// }

const maybe2 = Effect.option(Effect.fail("Uh oh!"))

Effect.runPromiseExit(maybe2).then(console.log)
// Output:
// {
//   _id: 'Exit',
//   _tag: 'Success',
//   value: { _id: 'Option', _tag: 'None' }
// }

const maybe3 = Effect.option(Effect.die("Boom!"))

Effect.runPromiseExit(maybe3).then(console.log)
// Output:
// {
//   _id: 'Exit',
//   _tag: 'Failure',
//   cause: { _id: 'Cause', _tag: 'Die', defect: 'Boom!' }
// }

See

• either for a version that uses Either instead.
• exit for a version that encapsulates both recoverable errors and defects in an Exit.

Signature

declare const option: <A, E, R>(self: Effect<A, E, R>) => Effect<Option.Option<A>, never, R>

Source

Since v2.0.0