On Wed, 19 Mar 2025 at 21:49, Adam Gundry via ghc-steering-committee <ghc-steering-committee@haskell.org> wrote:

Hi everyone,

This proposal [0] has been lingering for quite some time, unfortunately.
So we can make progress, I've tried to summarise our options below;
please vote for your preferred option in the next week or two. Once we
have decided on our preferred course of action, I'll make any necessary
editorial changes to the proposal.

To recap, the idea is to extend OverloadedRecordDot such that it permits
record selection expressions such as

foo.type -> getField @"type" foo

even though `type` is a keyword and hence not a valid record field in a
traditional datatype declarations. This is primarily motivated by the
use of OverloadedRecordDot in libraries such as `persistent` (see [1]),
which will generate instances like this:

instance HasField "type" SomeRecord SomeField1 where
getField = ...

instance HasField "bar" SomeRecord SomeField2 where
getField = ...

Both these instances are accepted, so it is quite surprising and
annoying that `foo.type` is a syntax error, even though `foo.bar` will
be accepted (and turn into a call to `getField @"bar"`).

As a small syntactic change, the proposal has lead to quite some
discussion and a few plausible alternatives:

A. Accept the proposal as it stands, since it is the smallest change
that resolves the issue.

B. Extend the proposal to permit still wider syntax, e.g.
`foo.Uppercase` or `foo."quoted string"`, motivated by consistency with
OverloadedLabels and use cases such as [2]. This seems reasonable to me.

C. Extend the proposal to permit keywords such as `type` to be used as
field names in traditional record syntax, e.g. `data Foo = Foo { type ::
Int }`. In my view this is unnecessary complexity that mistakenly
conflates OverloadedRecordDot with traditional record syntax; the
motivation for keywords as selector names comes from uses of
OverloadedRecordDot that do not involve traditional record syntax.

D. Reject the proposal entirely, e.g. due to worries about syntax
highlighting.

Please reply with your preference order amongst these options. My vote
is B > A > C > D.

Thanks,

Adam

[0] https://github.com/ghc-proposals/ghc-proposals/pull/668

[1]
https://github.com/ghc-proposals/ghc-proposals/pull/668#issuecomment-2561282397

[2]
https://github.com/ghc-proposals/ghc-proposals/pull/668#issuecomment-2564274901

On 05/11/2024 13:58, Arnaud Spiwack wrote:
> I have no opinion on this. But I've seen two points in the thread which
> make sense: Vlad, our guardian of the parser, says that it's a good
> idea, and the comparison with OverloadedLabel (made by Vlad and others)
> is apt, and the symmetry is desirable. Ideally the comparison with
> OverloadedLabel should be made in the Alternatives section, but I don't
> feel like insisting about it :) .
>
> On Sat, 2 Nov 2024 at 21:21, Simon Peyton Jones
> <simon.peytonjones@gmail.com <mailto:simon.peytonjones@gmail.com>> wrote:
>
> I'm in support too, but I have made some substantive suggestions on
> the GitHub ticket that I'd like to see addressed before we tie a bow
> on this.
>
> Simon
>
> On Sat, 2 Nov 2024 at 09:25, Sebastian Graf <sgraf1337@gmail.com
> <mailto:sgraf1337@gmail.com>> wrote:
>
> I'm in support as well, but would like to see a single
> clarifying sentence added to the proposal.
> https://github.com/ghc-proposals/ghc-proposals/pull/668#discussion_r1826533003 <https://github.com/ghc-proposals/ghc-proposals/pull/668#discussion_r1826533003>
>
> Am Sa., 2. Nov. 2024 um 07:29 Uhr schrieb Erik de Castro Lopo
> <erikd@mega-nerd.com <mailto:erikd@mega-nerd.com>>:
>
>
>
> I am in support.
>
> Erik
>
> Matthías Páll Gissurarson wrote:
>
> > I’m in support. No need to keep reservations longer than
> necessary.
> >
> > /Matti Palli
> >
> >
> > On Fri, Nov 1, 2024 at 23:22 Malte Ott
> <malte.ott@maralorn.de <mailto:malte.ott@maralorn.de>> wrote:
> >
> > >
> > > On 2024-10-29 20:12, Adam Gundry wrote:
> > > >
> https://github.com/ghc-proposals/ghc-proposals/pull/668
> <https://github.com/ghc-proposals/ghc-proposals/pull/668>
> > >
> > > I’m in support.
> > >
> > > Best
> > > Malte
> > > _______________________________________________
> > > ghc-steering-committee mailing list
> > > ghc-steering-committee@haskell.org
> <mailto:ghc-steering-committee@haskell.org>
> > >
> https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee <https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee>
> > >
>
>
> --
> ----------------------------------------------------------------------
> Erik de Castro Lopo
> http://www.mega-nerd.com/ <http://www.mega-nerd.com/>
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>
> --
> Arnaud Spiwack
> Director, Research at https://moduscreate.com <https://moduscreate.com>
> and https://tweag.io <https://tweag.io>.
>
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--
Adam Gundry, Haskell Consultant
Well-Typed LLP, https://www.well-typed.com/

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