API improvement ideas (usable behind @beta flag on npm)

Just writing this here publicly to see if others agree or disagree.

I think it would be nice to have a utility function that has the following signature:

Promise<Result<T, E>> => ResultAsync<T, E>

Since sometimes it’s easier to write a function using async/await syntax.

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Additionally, I am also thinking it would be nice to have another utility function with the following signature:

Result<T, E> => ResultAsyncT, E>

I guess the above would be called intoResultAsync or something like that?

Curious to hear what folks think.

[supermacro]

Released a combine utility function behind a @beta flag on npm!

Docs on combine: https://github.com/supermacro/neverthrow/releases/tag/v2.8.0-beta.0

Source code: https://github.com/supermacro/neverthrow/blob/master/src/utils.ts

Feedback always welcome!

[paduc]

Here’s an example right now that I think justifies having a Promise<Result<T, E>> => AsyncResult<T, E> function:

I personally never use Promise<Result> in my code because if there’s a Result inside a function, it means that I have control over what’s happening inside and can make that function return a ResultAsync. Also, once you have a Promise, the caller will have to await it and you push the untyped error problem up the call chain. My principle is to transform the Promises into ResultAsync at the lowest level (third-party api / io) and use ResultAsync everywhere in my code.

For your example, in which I guess your point is to call both getSingleSite and getSiteComments simultaneously, I would have written

const getSiteAndComments = (siteId: string): ResultAsync<SiteAndComments, RouteError> => {
  return ResultAsync.fromPromise(Promise.all([
    getSingleSite(siteId),
    getSiteComments(siteId),
  ])).andThen(([siteResult, commentsResult]) => {
    if (commentsResult.isErr()) {
      return commentsResult
    }
    if (siteResult.isErr()) {
      return siteResult
    }

    return ok({
      site: siteResult.value,
      comments: commentsResult.value,
    })
}

Maybe we could add a utility equivalent to Promise.all.