Result

Safely handle asynchronous errors with Result. Inspired by neverthrow's core ResultAsync types, but is intended for use in sequential imperative statements using async/await, rather than functional pipelining.

Akin to Rust's std::result and Scala's scala.util.Either. Uses ES2020's Promise.allSettled under the hood and mostly follows its naming convention.

Installation

npm i @00f2ff/result

API

E defaults to Error.

settle<T, E>

Settles a promise into Result<T, E> that can be narrowed to Fulfilled<T, E> or Rejected<T, E>.

const result: Result<boolean, Error> = await settle(Promise.resolve(true));
if (result.isFulfilled()) { 
  console.log(result.value); // true
}

const result: Result<boolean, Error> = await settle(Promise.reject(new Error("oh no"));
if (result.isRejected()) { 
  console.log(result.error); // Error("oh no")
}

settleAll<T, E>

Settles an array of promises into a tuple of [Fulfilled<T, E>[], Rejected<T, E>[]].

const resolvingPromises = [Promise.resolve(true), Promise.resolve("hello")];
const rejectingPromises = [Promise.reject(new Error("oh no"), Promise.reject(new DbError("ruh roh"))];

const [fulfilled, rejected] = await settleAll<boolean | string, Error | DbError>([...resolvingPromises, ...rejectingPromises]);

Test

npm run test