[ghc-steering-committee] Extra Commas
Simon Peyton Jones
simonpj at microsoft.com
Thu Apr 18 07:11:06 UTC 2019
Just to remind everyone, here's the proposal
https://github.com/parsonsmatt/ghc-proposals/blob/trailing-leading-commas/proposals/0000-trailing-leading-commas-subexports.rst
I think the TupleSections conflict means that the proposal does *not* plan to allow leading or trailing commas in tuples. That's an exception, but has no other technical difficulty.
I wonder if, for uniformity, the same exception should be made for constraint tuples, disallowing
f :: (Monad m,) => blah
because constraint tuples *are* really just tuples, and perhaps (Monad m,) :: Constraint -> Constraint.
The proposal has a "maybe" for pattern guards, so we don't have a clear recommendation from the author there.
But aside from these points I see not great difficulty. It's a superficial syntactic change (like putting 'qualified' in a different place; some people like it, and no harm is done to people who don't want it.
Simon
| -----Original Message-----
| From: ghc-steering-committee <ghc-steering-committee-bounces at haskell.org>
| On Behalf Of Joachim Breitner
| Sent: 17 April 2019 23:31
| To: ghc-steering-committee at haskell.org
| Subject: Re: [ghc-steering-committee] Extra Commas
|
| Hi,
|
| Am Mittwoch, den 17.04.2019, 13:38 -0500 schrieb Christopher Allen:
| > I gave my recommendation for ExtraCommas, acceptance of the original
| > proposal as written. I talk with the proposer almost every day so I
| > know where he stands. He still thinks it's worth doing and would like
| > to see it accepted. I think ExtraCommas merits acceptance. If we can't
| > achieve consensus on it then it should be rejected so it gets cleared
| > off the slate. I'm not inclined to argue a syntactic extension like
| > this, but I will say this:
| >
| > The proposal captures a nice design element that we've seen work very
| > well ergonomically in Rust. We're never going to make the same
| > decisions with the same tradeoffs as a totally different language but
| > any time there is a relatively isolated "good idea" like this, I'd
| > like to see us try to take advantage of that and see if it works for
| > us.
|
| thanks for picking this up.
|
| The most contentious point, besides whether its worth the bother at all,
| was the interaction with TupleSections. Which gives us three options, I
| think:
| * reject
| * accept, covering tuples (and making it conflict with TupleSections)
| * accept, not covering tuples.
|
| No decision is absolutely wrong, none is obviously right.
|
| Maybe we should simply do a vote, to get it decided? Simons (as Chairs),
| what do you think?
|
| Cheers,
| Joachim
|
| --
| Joachim Breitner
| mail at joachim-breitner.de
| http://www.joachim-breitner.de/
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