[ghc-steering-committee] Please review #496: Nothing {}, Shepherd: Eric

[Richard Eisenberg]

I've been away, but I just wanted to chime in that I'm in support.

Richard

> On Jun 24, 2022, at 6:29 AM, Simon Peyton Jones <simon.peytonjones at gmail.com> wrote:
> 
> As I say on the proposal thread, I'm in favour.
> 
> I do want John to fix the bug in the text  <https://github.com/ghc-proposals/ghc-proposals/pull/496#issuecomment-1153303273>though.
> 
> Simon
> 
> On Sun, 12 Jun 2022 at 17:19, Eric Seidel <eric at seidel.io <mailto:eric at seidel.io>> wrote:
> Dear Committee,
> 
> This proposal notes an inconsistency around record wildcard syntax where the wildcard selector/binder cannot be used with nullary record constructors. In other words
> 
> ```
> data Foo = Foo {}
> 
> x = Foo {..}
> ```
> 
> is rejected with the error
> 
>     Illegal `..' notation for constructor ‘Bar’
>       The constructor has no labelled fields
> 
> John notes that this is unnecessary friction that also causes grief for code generators.
> 
> The proposal is to allow the use of record wildcard syntax with nullary constructors. Notably the proposal suggests allowing wildcard syntax with both nullary *records* and nullary positional data constructors, ie both of the following would be allowed.
> 
> ```
> data Foo = Foo {}
> data Foo = Foo
> 
> x = Foo {..}
> ```
> 
> I noted on GitHub that this leaves a small asymmetry[1], but I still recommend accepting the proposal as is.
> 
> As usual, please discuss the proposal's merits in this thread, and the technical details on GitHub.
> 
> [1]: https://github.com/ghc-proposals/ghc-proposals/pull/496#issuecomment-1153221981 <https://github.com/ghc-proposals/ghc-proposals/pull/496#issuecomment-1153221981>
> 
> Eric
> 
> On Mon, May 30, 2022, at 09:28, Joachim Breitner wrote:
> > Dear Committee,
> >
> > Empty records with {}
> > have been proposed by John Ericsson
> >
> >
> > https://github.com/ghc-proposals/ghc-proposals/pull/496 <https://github.com/ghc-proposals/ghc-proposals/pull/496>
> > https://github.com/Ericson2314/ghc-proposals/blob/empty-record-wildcards/proposals/0000-empty-record-wildcards.rst <https://github.com/Ericson2314/ghc-proposals/blob/empty-record-wildcards/proposals/0000-empty-record-wildcards.rst>
> >
> > This seems to be about straightening a corner case, so to say. I
> > suggest Eric as the shepherd.
> >
> > Please guide us to a conclusion as outlined in 
> > https://github.com/ghc-proposals/ghc-proposals#committee-process <https://github.com/ghc-proposals/ghc-proposals#committee-process>
> >
> > Thanks,
> > Joachim
> >
> >
> >
> >
> >
> >
> >
> > -- 
> > Joachim Breitner
> >   mail at joachim-breitner.de <mailto:mail at joachim-breitner.de>
> >   http://www.joachim-breitner.de/ <http://www.joachim-breitner.de/>
> >
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