[ghc-steering-committee] Extra Commas

Simon Peyton Jones simonpj at microsoft.com
Thu Apr 18 14:52:37 UTC 2019


|  "tuples included" means "incompatible with tuple sections" means "they are
|  mutually exclusive to a module."

You mean, some kind of new error message that says "these two extension are mutually incompatible".  I can't say I love this.  Let's just leave out tuples from ExtraCommas.

(Actually I could imagine [a,,b,] meaning \xy. [a,x,b,y], one day.  Maybe we omit list literals too?  Or would that break the key use-cases?

Simon

|  -----Original Message-----
|  From: Christopher Allen <cma at bitemyapp.com>
|  Sent: 18 April 2019 10:08
|  To: Simon Peyton Jones <simonpj at microsoft.com>
|  Cc: Eric Seidel <eric at seidel.io>; ghc-steering-committee at haskell.org
|  Subject: Re: [ghc-steering-committee] Extra Commas
|  
|  My understanding of previous discussions was that:
|  
|  
|  On Thu, Apr 18, 2019 at 2:17 AM Simon Peyton Jones <simonpj at microsoft.com>
|  wrote:
|  >
|  > But it's actually *incompatible* with TupleSections, so how shoule
|  >         (True,)
|  > be interpreted if both are on?
|  >
|  > S
|  >
|  > |  -----Original Message-----
|  > |  From: ghc-steering-committee
|  > | <ghc-steering-committee-bounces at haskell.org>
|  > |  On Behalf Of Christopher Allen
|  > |  Sent: 18 April 2019 04:19
|  > |  To: Eric Seidel <eric at seidel.io>
|  > |  Cc: ghc-steering-committee at haskell.org
|  > |  Subject: Re: [ghc-steering-committee] Extra Commas
|  > |
|  > |  I spoke with Matt, he's fine either way with or without tuples.
|  > |
|  > |  I'd prefer "with tuples" for consistency. I use tuples sometimes,
|  > | but  don't care about sectioning.
|  > |
|  > |  On Wed, Apr 17, 2019 at 8:15 PM Eric Seidel <eric at seidel.io> wrote:
|  > |  >
|  > |  > I favor accepting the proposal, with or without tuples. I've been
|  > | writing a bit of Rust recently, and agree with Chris about the
|  > | ergonomics  of trailing commas.
|  > |  >
|  > |  > On Wed, Apr 17, 2019, at 18:31, Joachim Breitner wrote:
|  > |  > > 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
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