[ghc-steering-committee] Please review #220: QualifiedImports, Shepherd: Simon M

Fri Sep 20 09:06:48 UTC 2019

On Thu, 19 Sep 2019 at 22:02, Simon Peyton Jones <simonpj at microsoft.com>
wrote:

> Simon appears to be saying that he doesn't mind.
>
>
>
> Sorry -- I expressed myself badly.  I support rejection.
>
>
>
> I was saying IF there was a consensus that we wanted to simply to change
> the language to a better design, THEN there’d be a case for flags,
> migration strategy etc.
>
>
>
> But there isn’t such a consensue.  So it’s just a question of how those
> who want qualified imports can get them.
>
>    - Now: by consistently using `import qualified`
>    - Under this proposal: by consistently using `{-# LANGUAGE
>    QualifiedImports #-}`
>
> Both are coding conventions that might be enforced locally within, say, a
> company. But the convenience benefit of moving from the former to the
> latter doesn’t seem justified to me.
>

I think I was a bit unclear too, sorry - the second bullet point is what I
mean by a "fork", which is the thing I think we should strive to avoid.
Why is this a fork?

   - It fails the test "Is this extension something that most people would
   be happy to enable, even if they don't want to use it?"
   - It fails the test "Do we think there's a reasonable chance this
   extension will make it into a future language standard?"

The idea is that unless we can see a path to a point where everyone has the
extension turned on, we're left with different groups of people using
incompatible dialects of the language. A similar problem arises with
extensions that are mutually incompatible.

For extensions that are invasive and break a lot of code, I think we have
to establish that this is the right direction to move in. Or perhaps, that
this is something we think is worthwhile experimenting with (but that's
debatable, because it's hard to undo later).

Cheers
Simon

>
>
> Simon
>
>
>
> *From:* Simon Marlow <marlowsd at gmail.com>
> *Sent:* 19 September 2019 19:03
> *To:* Simon Peyton Jones <simonpj at microsoft.com>
> *Cc:* Richard Eisenberg <rae at richarde.dev>; Spiwack, Arnaud <
> arnaud.spiwack at tweag.io>; ghc-steering-committee at haskell.org; Joachim
> Breitner <mail at joachim-breitner.de>; Sandy Maguire <sandy at sandymaguire.me>
> *Subject:* Re: [ghc-steering-committee] Please review #220:
> QualifiedImports, Shepherd: Simon M
>
>
>
> The bigger question here is: are we happy to admit extensions that fork
> the language? Simon appears to be saying that he doesn't mind. I'm strongly
> against a fork, unless it has a clear migration path and an endpoint.
>
>
>
> Cheers
>
> Simon
>
>
>
>
>
> On Tue, 17 Sep 2019 at 23:56, Simon Peyton Jones via
> ghc-steering-committee <ghc-steering-committee at haskell.org> wrote:
>
> I agree with Arnaud that defaults are important: switching from opt-in to
> opt-out for organ donation, and for pension contributions, has had a huge
> effect.
>
>
>
> Suppose, as in the above examples, we had a consensus that
> import-qualified-by-default was the way we wanted Haskell to be.  Then we’d
> just be discussing how to switch over, what the deprecation strategy is,
> how many compiler releases to allow etc.  Controversial as it was, the
> Foldable thing was like this.
>
>
>
> But that’s not the case here.   We are not discussing a change to the base
> language, but a language extension that you can choose to use, or not.  So
> it remains a local coding style choice: “in our company we always use `{-#
> LANGUAGE QualifiedImports #-}` “.  But that really isn’t significantly
> different from saying “in our company we always use `import qualified`”.
> Yes, you can put the former in your .cabal file – but you could equally use
> HLint to enforce qualified import.
>
>
>
> I’m still not persuaded that this small change in convenience is enough to
> add an extension for.   As I say, it’d be different if there was a
> consensus that we wanted to change the base language, and migrate everyone
> to the new default.
>
>
>
> Simon
>
>
>
> *From:* ghc-steering-committee <ghc-steering-committee-bounces at haskell.org>
> *On Behalf Of *Richard Eisenberg
> *Sent:* 17 September 2019 22:04
> *To:* Spiwack, Arnaud <arnaud.spiwack at tweag.io>
> *Cc:* ghc-steering-committee at haskell.org; Joachim Breitner <
> mail at joachim-breitner.de>; Sandy Maguire <sandy at sandymaguire.me>
> *Subject:* Re: [ghc-steering-committee] Please review #220:
> QualifiedImports, Shepherd: Simon M
>
>
>
> I think Arnaud's is an effective argument. It has not changed my opinion
> of this proposal (I'm still against), but it's moved the needle a bit for
> me. What it does suggest is a feature in HLint (if it doesn't already
> exist) that encourages this behavior. Putting this in HLint allows
> individuals and organizations to experiment with enforcing this style,
> perhaps building up further experience for retrying this in the future.
>
>
>
> After writing the above, I talked to Arnaud, and he pointed out a deadly
> flaw in this plan: even if qualified is the default, it might sometimes be
> nice to import unqualified. In the proposal, this is done via the
> unqualified keyword. But without this proposal, there would be no way to
> signal to HLint that an import is meant to be unqualified. So perhaps a
> much more modest proposal allowing (but not requiring) users to write
> `unqualified` in import statements would be worthwhile. This keyword would
> always be redundant today, but it might feasibly be a way forward here.
>
>
>
> Full disclosure: my immediate instinct would be to be against the
> "unqualified" proposal, but it wouldn't be a fork of the language (unlike
> the current proposal). Perhaps others could convince me otherwise.
>
>
>
> Richard
>
>
>
> On Sep 17, 2019, at 7:52 AM, Spiwack, Arnaud <arnaud.spiwack at tweag.io>
> wrote:
>
>
>
> Dear all,
>
>
>
> As one of the author of this proposal. I am, unsurprisingly, against
> rejecting it. Though it seems I'm rather in a minority here, let me add one
> last argument to try and sway the general opinion. Being understood that
> being an author, this argument cannot, in any way be considered as “a vote”
> or any such thing.
>
>
>
> Human psychology is powerful. As it happens, we have a very strong
> tendency to choose whatever course of thought or action requires the least
> mental effort. Defaults require very little mental efforts, so we naturally
> will gravitate towards default. This is why, for instance, almost every
> Swedish worker is part of a union, while almost every French worker isn't:
> in Sweden, unionising is opt-out, whereas in France, it's opt-in. That's
> also why putting apples in front of sweet deserts in a school restaurant
> will result in more children eating fruits rather than cakes.
>
>
>
> Back to our case: the overwhelming majority of Haskell packages are
> designed to be used unqualified (and also do almost all of their imports
> unqualified). Now, either unqualified import are really that much better,
> or the default has an enormous influence. As I previously mentioned, in
> Ocaml, a fairly similar language, qualified is the default, and almost
> every libraries are designed for qualified imports, and import their
> modules qualified. So I'd wager it's the default.
>
>
>
> As a software architect, I do actually spend a bunch of my code reviews
> saying: you should import qualified. It would be a much more effective and
> powerful message to simply set the default imports as being qualified in my
> projects. For me, the change in this proposal would really be a very
> significant change.
>
>
>
> Now, the committee may decide that this is still not worth the confusion
> implied by having two incompatible syntactic conventions out there. That's
> entirely fair! I just don't want anybody to walk out of this conversation
> with the feeling that this proposal is an inconsequential stylistic change.
>
>
>
> /Arnaud
>
>
>
> On Mon, Sep 16, 2019 at 2:04 PM Sandy Maguire <sandy at sandymaguire.me>
> wrote:
>
> I'm happy with your reasoning, Simon, and am also in favor of rejection.
>
>
>
> On Mon, Sep 16, 2019 at 9:23 AM Simon Marlow <marlowsd at gmail.com> wrote:
>
> Dear steering committee -
>
>
>
> The discussion following my earlier suggestion to reject the proposal has
> petered out. Taking into account the discussion, it still seems to me that
> we should reject the proposal, so I've posted on the thread to this effect:
> https://github.com/ghc-proposals/ghc-proposals/pull/220#issuecomment-531666589
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F220%23issuecomment-531666589&data=02%7C01%7Csimonpj%40microsoft.com%7C662994f33a3549cdb22908d73d2ba0f0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637045129901224188&sdata=ebgD0GeRlMEG9p9%2FmqNiIFstG8hNQqSW2RtT8W3y7fQ%3D&reserved=0>
>
>
>
> Any further comments before we close it?
>
>
>
> Thanks
>
> Simon
>
>
>
> On Fri, 5 Jul 2019 at 08:19, Simon Marlow <marlowsd at gmail.com> wrote:
>
> Dear steering committee -
>
>
>
> I am inclined to reject this proposal, so as per the new committee process
> I posted the rationale on the github thread:
> https://github.com/ghc-proposals/ghc-proposals/pull/220#issuecomment-508414602
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F220%23issuecomment-508414602&data=02%7C01%7Csimonpj%40microsoft.com%7C662994f33a3549cdb22908d73d2ba0f0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637045129901234180&sdata=Jhy3R%2B2nE2rgO8bbbr45cfVvVLT95iLPqv5Kt3U%2B1BU%3D&reserved=0>
>
>
>
> You may want to consider the proposal and offer opinions while we wait for
> the authors' rebuttal. It's a very simple proposal.
>
>
>
> Cheers
>
> Simon
>
>
>
> On Wed, 3 Jul 2019 at 08:55, Joachim Breitner <mail at joachim-breitner.de>
> wrote:
>
> Dear Committee,
>
> this is your secretary speaking:
>
> QualifiedImports
> has been proposed by Arnaud Spiwack and Guillaume Bouchard
> https://github.com/ghc-proposals/ghc-proposals/pull/220
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F220&data=02%7C01%7Csimonpj%40microsoft.com%7C662994f33a3549cdb22908d73d2ba0f0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637045129901234180&sdata=bONeThtWR25ADAyUjypHr1V2q4c6TWM9Z2i41n2WBo4%3D&reserved=0>
>
> https://github.com/tweag/ghc-proposals/blob/qualified-import/proposals/0000-default-qualified-import.rst
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftweag%2Fghc-proposals%2Fblob%2Fqualified-import%2Fproposals%2F0000-default-qualified-import.rst&data=02%7C01%7Csimonpj%40microsoft.com%7C662994f33a3549cdb22908d73d2ba0f0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637045129901244176&sdata=9LyfLVT1wSTTXfgf0tsxdUfUzla2PYhU5QIgVxlrrCk%3D&reserved=0>
>
> I propose Simon M as the shepherd.
>
> Please reach consensus as described in
> https://github.com/ghc-proposals/ghc-proposals#committee-process
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%23committee-process&data=02%7C01%7Csimonpj%40microsoft.com%7C662994f33a3549cdb22908d73d2ba0f0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637045129901244176&sdata=3cQMiAXEoUgLmnD00dLG7vlvMyG6%2BXmdliFuTKkRXlc%3D&reserved=0>
> In particular, talk to the authors before, if you think this should be
> rejected, and kick off the discussion on Github, following the steps
> described under “Now the shepherd proposes to accept or reject the
> proposal” in the above link.
>
> Thanks,
> Joachim
> --
> Joachim Breitner
>   mail at joachim-breitner.de
>   http://www.joachim-breitner.de/
> <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.joachim-breitner.de%2F&data=02%7C01%7Csimonpj%40microsoft.com%7C662994f33a3549cdb22908d73d2ba0f0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637045129901254171&sdata=NqG1aixWIT%2BgIqXMH3o3SjoMdRywRUwhwQJUpOqFYC0%3D&reserved=0>
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