un-deprecate Lwt_result

[c-cube]

I still don't really understand why the module was deprecated, but the more I use lwt the more I can't bear with exception-based error handling in it. I think a well-developped, convenient Lwt_result module is critical for good error handling. Can we use this issue to discuss the future of Lwt_result then?

[samoht]

I concur. This is a very useful module which does not have other counter parts in the library ecosystem.

[aantron]

FWIW, I gave this a +1, but I have to delay making a positive decision on this due to time constraints. Any links for future reading, libraries that do this right (probably Async), in-depth discussion, etc., appreciated.

[agarwal]

Related modules from Async:

• Deferred.Result
• Deferred.Or_error.List. For some reason there is no Deferred.Result.List, which could be easily provided and would be more general than Deferred.Or_error.List. In case you don't know: 'a Or_error.t = ('a, Error.t) Result.t.

[c-cube]

For those interested, follow-up design issues in #324.

[aantron]

Thanks!

[tte]

@aantron Hello! So what is a replacement for Lwt_result? I was really excited to using this module instead of spaghetti-code checks w/ Lwt.Infix and Result monads. But I can't compile, run CI w/ -warn-error flag now. Why this (experimental) module is deprecated and what is a replacement for?

[aantron]

@tte this module is not deprecated or experimental since Lwt 2.7.1 (April). It is a supported part of Lwt.