Moving ArgumentsDo forward

[Akio Takano]

Hi Andrew,

On 6 June 2016 at 16:37, Andrew Gibiansky <andrew.gibiansky at gmail.com> wrote:
> As the author of the proposal and extension, I'd like to clarify that the
> change was abandoned per se because of how controversial the change was. [0]
> [1] [2]

Thank you for the clarification. I hope you don't mind that I pick up
your proposal and use your code as a starting point.

>
> This is not to say that we should not continue to discuss this change, but
> if we do so, make sure that you first read through the previous discussion
> -- it was quite extensive!
>
> Specifically, I became unconvinced that it was worth the effort to make as
> an extension, given the reasons against it (mainly, extra work for GHC,
> hindent, haskell-src-exts, etc etc); I think this along with a few other
> things (trailing commas!) could make a significant improvement to cosmetic
> Haskell syntax, but perhaps one extension per character is a bit much for
> that. That said I have no idea how else a mythical Haskell' could get a
> cleaned up syntax if not through first being implemented as a GHC extension.

I actually found the response from people at haskell-cafe rather
encouraging. To me a 50% support seems high enough to justify an
implementation.

>
> Finally, you may be interested in ghc-reskin [3], which was a (slightly
> tongue-in-cheek) response to a lot of the discussion caused by this
> extension last time, and could potentially be made into a production-ready
> tool / Haskell' syntax if anyone cared strongly to do so.

Thank you. Unfortunately for my uses a separate preprocessor probably
would have too much overhead.

>
> [0]
> https://www.reddit.com/r/haskell/comments/447bnw/does_argument_do_have_a_future/
> [1]
> https://mail.haskell.org/pipermail/haskell-cafe/2015-September/121217.html
> [2] https://ghc.haskell.org/trac/ghc/ticket/10843
> [3] https://github.com/gibiansky/ghc-reskin
>
> Best,
> Andrew
>
> On Wed, Jun 1, 2016 at 3:26 PM Akio Takano <tkn.akio at gmail.com> wrote:
>>
>> Hi Bardur,
>>
>> On 2 June 2016 at 00:09, Bardur Arantsson <spam at scientician.net> wrote:
>> > On 06/01/2016 01:48 PM, Akio Takano wrote:
>> >> Hi,
>> >>
>> >> Ticket #10843 [0] proposes an extension, ArgumentsDo, which I would
>> >> love to see in GHC. It's a small syntactic extension that allows do,
>> >> case, if and lambda blocks as function arguments, without parentheses.
>> >> However, its differential revision [1] has been abandoned, citing a
>> >> mixed response from the community. A message [2] on the ticket
>> >> summarizes a thread in haskell-cafe on this topic.
>> >>
>> >> I, for one, think adding this extension is worthwhile, because a
>> >> significant number of people support it. Also, given how some people
>> >> seem to feel ambivalent about this change, I believe actually allowing
>> >> people to try it makes it clearer whether it is a good idea.
>> >>
>> >> Thus I'm wondering: is there any chance that this gets merged? If so,
>> >> I'm willing to work on whatever is remaining to get the change merged.
>> >>
>> >
>> > What's changed since it was last discussed?
>>
>> Nothing has really changed. I'm just trying to argue that the current
>> level of community support is good enough to justify an
>> implementation.
>>
>> Please note that the previous Differential revision was abandoned by
>> the author. It was *not* rejected due to a lack of support. Hence my
>> question: if properly implemented, does this feature have any chance
>> of getting merged in, or is it regarded too controversial?
>>
>> > I don't think the objections
>> > were centered in the implementation, so I don't see what "whatever is
>> > remaining to get the change merged" would be.
>>
>> I'm referring the points mentioned in the review comments in the
>> Differential revision. For example this change needs an update to the
>> User's Guide.
>>
>> >
>> > AFAICT at best it's a *very* small improvement[1] and fractures Haskell
>> > syntax even more around extensions -- tooling etc. will need to
>> > understand even *more* syntax extensions[2].
>>
>> I disagree that this is a small improvement, but I don't intend to
>> debate this here. As you said, nothing has really changed since it was
>> discussed before, and a lot of reasons for implementing this extension
>> have been already pointed out. I don't have anything to add.
>>
>> Regarding tooling, my understanding is that most tools that need to
>> understand Haskell (this includes ghc-mod and hdevtools) use either
>> the GHC API or haskell-src-exts, so I don't think this extension would
>> need changes in many places.
>>
>> Regards,
>> Takano Akio
>>
>> >
>> > Regards,
>> >
>> > [1] If you grant that it is indeed an improvment, which I, personally,
>> > don't think it is.
>> >
>> > [2] I think most people agree that this is something that should perhaps
>> > be handled by something like
>> > https://github.com/haskell/haskell-ide-engine so that it would only need
>> > to be implemented once, but there's not even an alpha release yet, so
>> > that particular objection stands, AFAICT.
>> >
>> >
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>
> --
>
> – Andrew
>
>
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