[ghc-steering-committee] Please review: Mutable constructor fields, Shepherd: Ryan Newton

[Simon Peyton Jones]

which are the highest priority, deal-breaker issues for you?
As I say, I’m uncomfortable, but since I can’t identify anything solidly wrong with it, I don’t want to stand in the way.

Once we have a full implementation, and can see the impacts on the codebase, we may be in a better position to judge. (This is true of every proposal whose impacts across the compiler are hard to predict, not just this one.)

If we require at least one mutable field for a constructor to have physical equality, then reallyUnsafePtrEq# can be avoided both in derived or handwritten equality functions

Well, of course you need at least one mutable field!  But having got it, how do we get rid of the unsafe-ptr-eq?  Perhaps the thing to do is to update the proposal to whatever the new idea is?

Simon

From: Ryan Newton [mailto:rrnewton at indiana.edu]
Sent: 03 March 2018 23:14
To: Simon Marlow <marlowsd at gmail.com>; Simon Peyton Jones <simonpj at microsoft.com>
Cc: Joachim Breitner <mail at joachim-breitner.de>; ghc-steering-committee at haskell.org
Subject: Re: [ghc-steering-committee] Please review: Mutable constructor fields, Shepherd: Ryan Newton

I'm certainly fine with going back to discussion.

Simon PJ, much of your review was improvements/edits, and after those are incorporated, which are the highest priority, deal-breaker issues for you?

In particular, the requirement to use reallyUnsafePtrEq# received some subsequent discussion.  If we require at least one mutable field for a constructor to have physical equality, then reallyUnsafePtrEq# can be avoided both in derived or handwritten equality functions.  Does that improve your assessment?

Best,
 -Ryan



On Thu, Mar 1, 2018 at 3:48 AM, Simon Marlow <marlowsd at gmail.com<mailto:marlowsd at gmail.com>> wrote:
Simon has provided a detailed review (thanks!) so I think we'll need some time to digest those comments and suggestions and modify the proposal. In light of that shall we put the proposal back into the discussion phase for now?
Cheers
Simon

On 1 March 2018 at 05:17, Joachim Breitner <mail at joachim-breitner.de<mailto:mail at joachim-breitner.de>> wrote:
Hi,

Am Freitag, den 23.02.2018, 15:22 -0500 schrieb Ryan Newton:
> Ok, I'm not hearing any strong objections and over the long course of
> discussion in various venues, reactions have been mostly positive.
> Since committee discussion here has died down, I move to go ahead and
> accept this proposal if there are no further objections.

it has been quiet here, but I see new activity on
https://github.com/ghc-proposals/ghc-proposals/pull/8<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F8&data=04%7C01%7Csimonpj%40microsoft.com%7C0fbe8d22dcbd49db82bd08d5815c8c66%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636557156850040805%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwifQ%3D%3D%7C-1&sdata=0V4RHBIaGCfrcdDceNHqqgME11gjUc7o78vGYO2Xfog%3D&reserved=0>

Is this a sign that the proposal is not yet as polished as would hope
for?

Joachim

--
Joachim “nomeata” Breitner
  mail at joachim-breitner.de<mailto:mail at joachim-breitner.de>
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