function request: Lwt.ignore

[jrochel]

Lwt.ignore = Lwt.map ignore

[Drup]

There is already Lwt.ignore_result, do you really need the thread when you are ignoring ?

[jrochel]

I thought such a function to be convenient in order to shorten code of the form:

let%lwt = some_lwt_action () in
Lwt.return_unit

to:

Lwt.ignore @@ some_lwt_action ()

which would be the lwt equivalence of

ignore @@ some_pure_action ()

While

some_lwt.action () >> Lwt.return_unit

would be fine too, >> is awkward to qualify.

[aantron]

I typically write

some_lwt_action () >|= ignore

with Lwt.Infix open in scope. Is this not suitable?

[aantron]

There is also

Lwt.async some_lwt_action    (* : unit *)

which is a bit different from Lwt.ignore_result, because Lwt.ignore_result can raise an exception immediately (whereas Lwt.async will confidently terminate your process unless you take steps to avoid that :p).

[Drup]

(well, Lwt.ignore_result is also a serious anti-pattern and people should probably never use it, but that's another discussion :p)

[jrochel]

| some_lwt_action () >|= ignore

@aantron: It is suitable but... I guess as a Haskeller I'm still struggeling with... a cultural issue. Ater a year of OCaml programming I'm still trying to get a feel on the attitude of the OCaml community towards extending libraries with new generic functions. So far I percieve this attitude as very conservative. Personally I would love to have a common language shared by various "monads" such as Pervasives and Lwt, but I guess this is the cultural gap I have to learn to accept...

[jrochel]

| some_lwt_action () >|= ignore

@aantron: It is suitable but... I guess as a Haskeller I'm still struggeling with... a cultural issue. Ater a year of OCaml programming I'm still trying to get a feel on the attitude of the OCaml community towards extending libraries with new generic functions. So far I percieve this attitude as very conservative. Personally I would love to have a common language shared by various "monads" such as Pervasives and Lwt, but I guess this is the cultural gap I have to learn to accept...

[aantron]

It's definitely important to have a common language between monads. I wish this was the case, too. However, I think, unless people get together and explicitly make that a shared focus, it will have to wait until modular implicits are added to the language, or something like that.

For extending Lwt specifically, I'm not particularly against it in the long term. However, at this time, Lwt has quite a bit of technical debt, which consumes the time, and patience, of maintainers and potential contributors. I'm really focused on decreasing that, which makes me temporarily biased against adding new APIs or features. So, while Lwt has this inward focus, it will be more conservative than might otherwise be ideal.

[jrochel]

I see. Thanks a lot for these explanations!

[aantron]

@jrochel you may be interested to know about this PR, which you may have seen already. It is aimed at taking Lwt out of its stasis.