effect-io-ai

Package: effect
Module: Effect

Effect.matchEffect

Handles both success and failure cases of an effect, allowing for additional side effects.

Details

The matchEffect function is similar to match, but it enables you to perform side effects in the handlers for both success and failure outcomes.

When to Use

This is useful when you need to execute additional actions, like logging or notifying users, based on whether an effect succeeds or fails.

Example (Handling Both Success and Failure Cases with Side Effects)

import { Effect } from "effect"

const success: Effect.Effect<number, Error> = Effect.succeed(42)
const failure: Effect.Effect<number, Error> = Effect.fail(
  new Error("Uh oh!")
)

const program1 = Effect.matchEffect(success, {
  onFailure: (error) =>
    Effect.succeed(`failure: ${error.message}`).pipe(
      Effect.tap(Effect.log)
    ),
  onSuccess: (value) =>
    Effect.succeed(`success: ${value}`).pipe(Effect.tap(Effect.log))
})

console.log(Effect.runSync(program1))
// Output:
// timestamp=... level=INFO fiber=#0 message="success: 42"
// success: 42

const program2 = Effect.matchEffect(failure, {
  onFailure: (error) =>
    Effect.succeed(`failure: ${error.message}`).pipe(
      Effect.tap(Effect.log)
    ),
  onSuccess: (value) =>
    Effect.succeed(`success: ${value}`).pipe(Effect.tap(Effect.log))
})

console.log(Effect.runSync(program2))
// Output:
// timestamp=... level=INFO fiber=#1 message="failure: Uh oh!"
// failure: Uh oh!

See

• match if you don’t need side effects and only want to handle the result or failure.

Signature

declare const matchEffect: { <E, A2, E2, R2, A, A3, E3, R3>(options: { readonly onFailure: (e: E) => Effect<A2, E2, R2>; readonly onSuccess: (a: A) => Effect<A3, E3, R3>; }): <R>(self: Effect<A, E, R>) => Effect<A2 | A3, E2 | E3, R2 | R3 | R>; <A, E, R, A2, E2, R2, A3, E3, R3>(self: Effect<A, E, R>, options: { readonly onFailure: (e: E) => Effect<A2, E2, R2>; readonly onSuccess: (a: A) => Effect<A3, E3, R3>; }): Effect<A2 | A3, E2 | E3, R2 | R3 | R>; }

Source

Since v2.0.0