effect-io-ai

Package: effect
Module: Effect

Effect.matchCause

Handles failures by matching the cause of failure.

Details

The matchCause function allows you to handle failures with access to the full cause of the failure within a fiber.

When to Use

This is useful for differentiating between different types of errors, such as regular failures, defects, or interruptions. You can provide specific handling logic for each failure type based on the cause.

Example (Handling Different Failure Causes)

import { Effect } from "effect"

const task: Effect.Effect<number, Error> = Effect.die("Uh oh!")

const program = Effect.matchCause(task, {
  onFailure: (cause) => {
    switch (cause._tag) {
      case "Fail":
        // Handle standard failure
        return `Fail: ${cause.error.message}`
      case "Die":
        // Handle defects (unexpected errors)
        return `Die: ${cause.defect}`
      case "Interrupt":
        // Handle interruption
        return `${cause.fiberId} interrupted!`
    }
    // Fallback for other causes
    return "failed due to other causes"
  },
  onSuccess: (value) =>
    // task completes successfully
    `succeeded with ${value} value`
})

Effect.runPromise(program).then(console.log)
// Output: "Die: Uh oh!"

See

• matchCauseEffect if you need to perform side effects in the handlers.
• match if you don’t need to handle the cause of the failure.

Signature

declare const matchCause: { <E, A2, A, A3>(options: { readonly onFailure: (cause: Cause.Cause<E>) => A2; readonly onSuccess: (a: 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: (cause: Cause.Cause<E>) => A2; readonly onSuccess: (a: A) => A3; }): Effect<A2 | A3, never, R>; }

Source

Since v2.0.0