Re: [Caml-list] [ANN] Lwt 2.7.0 – monadic promises; concurrent I/O

[Ivan Gotovchits <ivg@ieee.org>]

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These are the great news!

And thanks for the maintainers notification, it was really helpful :)

I have one comment, though:



> Values of types 'a Lwt.t are now called promises rather than threads.
>   This should eliminate a lot of confusion for beginners.


And create a confusion for seasoned programmers, especially for those who
are accustomed to
C++ newly introduced concepts, like promises and futures, where a promise
has quite an opposite
meaning.  In short, it has the same meaning as a value of type  `'a Lwt.u`,
i.e., it is an object through
which a promise can be fulfilled. I think that it is better to refer to
Lwt.t threads as futures because they
are the values, whose value is determined in the future. Another way to
name them is `deferred`, again
for the same reason. You can also say, that a value of type `'a Lwt.t` is a
computation. You can also try
to borrow names from the Standard ML community, where `'a Lwt.t` like
objects are named as IVars.

Finally, you may also find this project interesting [1]. This is an
attempt to factor out the core idea from both
Core Async and Lwt. In particular, the Future library allows us to write a
monadic code, that is independent
of a particular implementation (Lwt or Async or Identity monad).

[1]:
https://github.com/BinaryAnalysisPlatform/bap/blob/master/lib/bap_future/bap_future.mli

On Fri, Jan 6, 2017 at 11:08 AM, Anton Bachin <antronbachin@gmail.com>
wrote:

> Greetings,
>
> I am pleased to announce release 2.7.0 of Lwt.
>
>   https://github.com/ocsigen/lwt
>
> The primary goals of this release are (1) to improve communication
> between maintainers and users, and (2) to prepare for (minor) breaking
> changes to some APIs in Lwt 3.0.0 (planned for April). The changelog is
> available here:
>
>   https://github.com/ocsigen/lwt/releases/tag/2.7.0
>
> - Lwt now uses deprecation warnings ([@deprecated]), especially for
>   upcoming breaking changes [1]. This required dropping support for
>   OCaml 4.01.
> - There is a gradual, communicative, conservative process for
>   deprecation and breaking [2]. Maintainers of packages in OPAM get
>   notified proactively (see [1] again). If you have code not published
>   in OPAM, watch the Lwt repo, recompile the code at least once in three
>   months, watch this mailing list, or subscribe to the Lwt announcements
>   issue [3].
> - If a planned breaking change is a bad idea, please let the maintainers
>   know when you see the warning.
> - Lwt now uses semantic versioning [4]. The major version will grow
>   slowly but steadily, but this does not mean that the whole API is
>   being redesigned or broken.
>
> If you are releasing a package to OPAM that depends on Lwt, it is not
> recommended to constrain Lwt to its current major version. A major
> release of Lwt will break only a few APIs, and your package is likely
> not to be affected – if it is, you will be notified. You may, however,
> wish to constrain Lwt to a major version in your private or production
> code.
>
> - The main OPAM package lwt is getting rid of some optional
>   dependencies in 3.0.0, which are now installable through separate OPAM
>   packages lwt_ssl, lwt_glib, lwt_react. This is to reduce recompilation
>   of Lwt when installing OPAM packages ssl, lablgtk, and react.
> - Values of types 'a Lwt.t are now called promises rather than threads.
>   This should eliminate a lot of confusion for beginners.
>
> Lwt 2.7.0 also has a number of more ordinary changes, such as bug fixes
> and the addition of bindings to writev and readv. See the full
> changelog [5].
>
> I am working on an all-new manual, including fully rewritten API
> documentation with examples. It should be ready towards the end of
> winter.
>
> My hope is that all the above allows Lwt to be taken progressively into
> the future, at the same time making development more open and more
> humane :)
>
> Best,
> Anton
>
>
> [1]: https://github.com/ocsigen/lwt/issues/308
> [2]: https://github.com/ocsigen/lwt/issues/293
> [3]: https://github.com/ocsigen/lwt/issues/309
> [4]: http://semver.org/
> [5]: https://github.com/ocsigen/lwt/releases/tag/2.7.0
>
>
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