fromPromise

@ts-rust/std

---

@ts-rust/std / Result / fromPromise

Function: fromPromise()

function fromPromise<T, E>(promise, mkErr): PendingResult<T, E>;

Defined in: packages/std/src/result/result.ts:526

Wraps a promise in a PendingResult, mapping rejection through mkErr.

This is the promise-taking counterpart of runAsync: pass an already created promise instead of a factory. If the promise fulfills, the pending result resolves to Ok. If it rejects, the reason is passed to mkErr and the pending result resolves to Err.

Type Parameters

Type Parameter
T
E

Parameters

Parameter	Type	Description
promise	PromiseLike<T>	A promise of the successful value.
mkErr	(error) => Awaited<E>	A function that converts a rejection reason into an error of type E.

Returns

PendingResult<T, E>

A PendingResult that resolves to Ok or Err.

Example

const pendingRes = fromPromise(
  fetch("https://api.example.com/text").then((res) => res.text()),
  (e) => new Error(`Fetch failed: ${JSON.stringify(e)}`),
);

const res = await pendingRes;

if (res.isErr()) {
  console.log(res.unwrapErr().expected?.message);
}