WIP Proposal: adding [Symbol.dispose] to check unhandled Result

[pnodet]

Typescript 5.2 introduced the using keyword. One thing that I find hard with neverthrow is checking for unhandled result. The eslint plugin brings helpful linter errors but I wanted to try implementing [Symbol.dispose] and see if it can help the DX.

[pnodet]

Maybe this can also be helpful for issues like #525

[supermacro]

I think having improvements to signal that you have unhandled / swalled errors in your stack would be awesome.

Are you able to provide examples of how this API would address this problem?

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[pnodet]

@supermacro Sorry, rebased this branch with upstream commits and GitHub closed it automatically.

This idea behind this is to leverage the Symbol.dispose new functionality.

const someFunc = () => {
  using anExampleResult = aFunctionReturningAResult();
}

for example this would throw an UnhandledResultError because at the end of someFunc the anExampleResult result has not been unwrap or match or another neverthrow result's method

[pnodet]

tbh this was more a wild idea that a real proposal bc I see several issues (people forgetting the using keyword, having error thrown in production…)

I'd be happy to improve this or keep working on it if you or others think it would be a great addition tho!

[supermacro]

@m-shaka @dmmulroy what are your thoughts?

[pnodet]

Also curious to know @mattpocock if you have thoughts on how to improve this or examples of more complex Symbol.dispose use cases

[mattpocock]

Don't see how using differs from just const here - using is meant for tidying up a resource when it leaves scope.

[pnodet]

With using we can leverage Symbol.dispose to do something like :

https://github.com/supermacro/neverthrow/pull/552/files#diff-fe54c0b0441ef7719a22666a2bb171f2db9e99c0ed52dd8fec96a9882e7c842dR405-R409

[mattpocock]

@pnodet Gotcha, that makes sense. Feels possible, but I'm not sure how intuitive the API will feel to most users.

[m-shaka]

I don't know if it's a use case of using. using can be used to manage "resource" with a specific lifetime. It sounds strongly connected to side-effects, which neverthrow has nothing to do with

Resource — An object with a specific lifetime, at the end of which either a lifetime-sensitive operation should be performed or a non-garbage-collected reference (such as a file handle, socket, etc.) should be closed or freed.

https://github.com/tc39/proposal-explicit-resource-management

[mattpocock]

Yeah, this feels like .unsafeUnwrap with extra steps.

[supermacro]

Identifying if a result is used or not should be done statically (prob through a linter) rather than at runtime, no? Closing for now