effect-io-ai

Package: effect
Module: Effect

Effect.match

Handles both success and failure cases of an effect without performing side effects.

Details

match lets you define custom handlers for both success and failure scenarios. You provide separate functions to handle each case, allowing you to process the result if the effect succeeds, or handle the error if the effect fails.

When to Use

This is useful for structuring your code to respond differently to success or failure without triggering side effects.

Example (Handling Both Success and Failure Cases)

import { Effect } from "effect"

const success: Effect.Effect<number, Error> = Effect.succeed(42)

const program1 = Effect.match(success, {
  onFailure: (error) => `failure: ${error.message}`,
  onSuccess: (value) => `success: ${value}`
})

// Run and log the result of the successful effect
Effect.runPromise(program1).then(console.log)
// Output: "success: 42"

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

const program2 = Effect.match(failure, {
  onFailure: (error) => `failure: ${error.message}`,
  onSuccess: (value) => `success: ${value}`
})

// Run and log the result of the failed effect
Effect.runPromise(program2).then(console.log)
// Output: "failure: Uh oh!"

See

• matchEffect if you need to perform side effects in the handlers.

Signature

declare const match: { <E, A2, A, A3>(options: { readonly onFailure: (error: E) => A2; readonly onSuccess: (value: A) => A3; }): <R>(self: Effect<A, E, R>) => Effect<A2 | A3, never, R>; <A, E, R, A2, A3>(self: Effect<A, E, R>, options: { readonly onFailure: (error: E) => A2; readonly onSuccess: (value: A) => A3; }): Effect<A2 | A3, never, R>; }

Source

Since v2.0.0