July 2021 - ghc-steering-committee

\cases
by Simon Peyton Jones 29 Jul '21

29 Jul '21

Folks I've had a final thought about \cases. Looking at it now, I wonder if we can simply expand what LambdaCase allows, rather than having yet another extension. That is, LambdaCase now accepts \cases as well as \case. If we'd designed it from scratch we certainly would not have had two different extensions. The only downside I can see is a loss of back-compat in this program {-# LANGUAGE LambdaCase #-} module Foo where f = \cases -> cases + 1 -- Adds 1 g = \case { True -> False, False -> True } If we extend what LambdaCase does, the definition of f will change its meaning. But this is so bizarre that I'm disinclined to waste time on it. My suggestion: expand what LambdaCase does. If not, the new extension should be LambdaCases. Can you reply on the GitHub? https://github.com/ghc-proposals/ghc-proposals/pull/302 Simon

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#302 \cases
by Simon Peyton Jones 27 Jul '21

27 Jul '21

Dear steering committee, See below - it seems that (1) is the winner. I have recorded the results on our document here<https://docs.google.com/document/d/1NDXk5kKcLtkqhkSNESAC9jVrBn3yqS_Qe1vacAI…>. I'll post on the GitHub. Thanks for participating in this. I think this ranked-preference voting works well when it comes down to a balance of taste on syntax, so that complete unanimity is unreasonable expectation. Simon From: Joachim Breitner <mail(a)joachim-breitner.de> Sent: 26 July 2021 21:19 To: Simon Peyton Jones <simonpj(a)microsoft.com> Subject: Re: Running the voting algorithm I'll do it by hand: Votes: 1 > X > 2 = 4 2 > 4 > X > 1 1 > 4 > 2 > X 1 > X > 2 = 4 2 > 1 > X > 4 X > 1 > 2 = 4 1 > X > 2 = 4 1 > 2 > X > 4 1 > X > 2 = 4 2 > X > 1 > 4 Let's see if 1 is the winner: 1 beats 2 by 7 vs. 3 votes 1 beats 4 by 9 vs. 1 votes 1 beats X by 7 vs. 3 votes The winner is 1. (This tally was created on the phone in a tent on a mountain above a Norwegian fjord.) 26.07.2021 13:31:36 Simon Peyton Jones <simonpj(a)microsoft.com<mailto:simonpj@microsoft.com>>: Joachim We have votes for \case, here https://docs.google.com/document/d/1NDXk5kKcLtkqhkSNESAC9jVrBn3yqS_Qe1vacAI…<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.goog…> Could you possibly run the voting algorithm - or tell me how to? Thanks Simon

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GHC proposals
by Simon Peyton Jones 12 Jul '21

12 Jul '21

Friends I'm a bit concerned that we are falling down on our commitment to decide about GHC proposals in a timely manner. Part of the problem is that at any moment I don't have a clear snapshot in my head of what decisions are pending, and who is driving them. I know that Joachim hates manual solutions, but I have spent a few minutes digging through my email to build * this spreadsheet giving the current status<https://docs.google.com/spreadsheets/d/1tt2BUtr6ws4YtdkM7f986pb8rid26-TyKxs…> You all have edit permissions. It covers only the handful of proposals that are in our court. Can I suggest that we all use it to keep ourselves on the ball? E.g. as a shepherd you can use it to record who you are waiting for, as I have done for #302. You'll notice that we are behind on every one of them. Remember, if there edits we want the author to make, we push it back, out of our court. It can re-enter when the author re-submits. If our commitments are over-ambitious, let's review them. Tom: you are our official nudger. Would you like to make you weekly nudge into an email to the full committee, with a pointer to the spreadsheet and your current understanding of who is responsible for driving? I hope this is helpful. If not, let's think of something else! Simon

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Stepping down for now
by Cale Gibbard 10 Jul '21

10 Jul '21

I've been having trouble finding time and energy to keep track of GHC steering committee stuff of late, so it's probably best if my place was assigned to someone else. I'll still be around of course, given that my work with Obsidian has me doing GHC development right now, but it's hard to do that, and then also find spare time for this. Thanks! - Cale

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GHC Steering Committee Status
by Joachim Breitner 01 Jul '21

01 Jul '21

Dear Committee, I had some busy months, so this status update is a bit later than expected… but you were all reasonably busy without me, so that’s fine. Over the summer I’ll be away from a laptop for a few weeks, so more than usually please keep tabs on your open tasks, and listen to Tom's nudges. So here’s the delta since May 17th. * Simon suggests a better way to keep tabs on what’s going on. Please join the that discussion! * Iavor left the committee. 👋 * we were asked to review these proposals: #351: NoIncomplete, Shepherd: Vitaly #281: Visible 'forall' in terms, Shepherd: Richard #390: Fine-grained pragmas, Shepherd: Vitaly (back from revision) * we have a recommendation from the shepherd about: #409: Exportable named defaults (partial accept) #283: Local modules (again) (accept) #351: NoIncomplete (accept) #281: Visible "forall" in terms (accept) #412: Explicit Splice Imports (accept) * we have sent the following proposals back to revision #400: Constrained COMPLETE sets (but it’s back already) * we decided about the following proposals #378: support the design for dependent types (accept) We currently have to act on the following 9 proposals, up by 1. ## Waiting for committee decision #281: Visible 'forall' in types of terms, Shepherd: Richard Richard recommends to accep this. It kicked off a discussion about points that one could argue have been covered by #378 already. Conversation has stalled since a month. Simon M, Richard, can you make progress on your conversation? #283: Local modules, Shepherd: Arnaud Arnaud recommends to accepts, and wants more opinions. Please give it! #302: Lambda expressions with guards and multiple clauses, Shepherd: SPJ Committee is preparing a vote #351: NoIncomplete, Shepherd: Vitaly Looks like it’s going to be rejected, since people are partial to -Wpartial instead. Waiting for the author to concur. #392: Clarify modifiers design principle (Shepherd: Alejandro) One comment only so far, please add more. #409: Exportable named defaults, Shepherd: Eric Deliberations about import behavior is going on. #412: splice imports, Shepherd: Vladislav Positive feedback so far. Shall we accept it, Vladislav? ## Waiting for Shepherd action #390: Fine-grained pragmas, Shepherd: Vitaly Vitaly, this is back from revision. What do you think about it? #400: Constrained COMPLETE sets, Shepherd: Vladislav Waiting for recommendation. Vladislav, the author says they addressed your concerns, and it’s now again in your court. Cheers, Joachim -- Joachim Breitner mail(a)joachim-breitner.de http://www.joachim-breitner.de/

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Proposal #302: `\of`
by Richard Eisenberg 01 Jul '21

01 Jul '21

Hi all, Proposal #302 was submitted to the committee and assigned to Cale. He has made a recommendation on the GitHub trail, but I don't believe the committee has discussed this among ourselves. PR: https://github.com/ghc-proposals/ghc-proposals/pull/302 Proposal: https://github.com/JakobBruenker/ghc-proposals/blob/patch-1/proposals/0000-… Cale's recommendation: https://github.com/ghc-proposals/ghc-proposals/pull/302#issuecomment-666075… The idea, in brief, is to introduce a new syntax (guarded behind -XMultiWayLambda) \of. Here is an example, which gives you the idea: mplus :: Maybe Int -> Maybe Int -> Maybe Int mplus = \of Nothing _ -> Nothing _ Nothing -> Nothing (Just x) (Just y) -> Just (x + y) The new keyword allows us to use a syntax similar to function definitions, but without repeating the name of the function. It is also like \case, but it allows multiple arguments. Guards are allowed, as usual. I really like this new syntax -- mostly because I find it very strange that we have to repeat the function name on every line. And then change the spacing when we change the function name. And I like the mnemonic "lambda of". And it allows me to write a where clause that is accessible in multiple different patterns, or an indented where clause that is usable in just one. If it didn't confuse readers, I would use this syntax all the time. Even so, I agree with Cale's recommendation to reject. We just have too much syntax! If someone were to come along and draft a concrete proposal of how we could, for example, use this syntax to replace both \case and if|, with a migration strategy, etc., then I might be in favor. Until then, I think we've spent our budget for cute, obscure bits of syntax. Richard

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