effect-io-ai

Package: effect
Module: Effect

Effect.catch

Recovers from a specified error by catching it and handling it with a provided function.

Details

This function allows you to recover from specific errors that occur during the execution of an effect. It works by catching a specific type of error (identified by a discriminator) and then handling it using a provided handler function. The handler can return a new effect that helps recover from the error, allowing the program to continue. If the error doesn’t match the specified type, the function allows the original effect to continue as it was.

Example

import { Console, Effect } from "effect"

class NetworkError {
  readonly _tag = "NetworkError"
}
class ValidationError {
  readonly _tag = "ValidationError"
}

// Simulate an effect that may fail
const task: Effect.Effect<never, NetworkError | ValidationError, never> = Effect.fail(new NetworkError())

const program = Effect.gen(function*() {
  const result = yield* Effect.catch(task, "_tag", {
    failure: "NetworkError",
    onFailure: (error) => Effect.succeed(`recovered from error: ${error._tag}`)
  })
  console.log(`Result: ${result}`)
})

Effect.runFork(program)
// Output: Result: recovered from error: NetworkError

See

• catchTag for a version that can recover from errors based on a _tag discriminator.

Signature

declare const catch: { <N extends keyof E, K extends E[N] & string, E, A1, E1, R1>(discriminator: N, options: { readonly failure: K; readonly onFailure: (error: Extract<E, { [n in N]: K; }>) => Effect<A1, E1, R1>; }): <A, R>(self: Effect<A, E, R>) => Effect<A1 | A, E1 | Exclude<E, { [n in N]: K; }>, R1 | R>; <A, E, R, N extends keyof E, K extends E[N] & string, A1, E1, R1>(self: Effect<A, E, R>, discriminator: N, options: { readonly failure: K; readonly onFailure: (error: Extract<E, { [n in N]: K; }>) => Effect<A1, E1, R1>; }): Effect<A | A1, E1 | Exclude<E, { [n in N]: K; }>, R | R1>; }

Source

Since v2.0.0