Re: Monad of no `return` Proposal (MRP): Moving `return` out of `Monad`

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Re: Breaking Changes and Long Term Support Haskell

Geoffrey Mainland
On 10/21/2015 07:30 AM, Simon Peyton Jones wrote:

> Friends
>
> I think it's good for us to debate the question of how we should balance innovation against change; and how we should make those decisions in future.  Geoff's message had some good ideas, especially this bit:
>
> |  Proposal 2: After a suitable period of discussion on the libraries list, the
> |  Core Libraries Committee will summarize the arguments for and against a
> |  proposal and post it, along with a (justified) preliminary decision, to a
> |  low-traffic, announce-only email list. After another suitable period of
> |  discussion, they will issue a final decision. What is a suitable period of
> |  time? Perhaps that depends on the properties of the proposal, such as
> |  whether it breaks backwards compatibility.
>
> Identifying major changes to the libraries, and having a better publicised, more RFC-like process for deliberating them, would be a good thing.  I believe that the Core Libraries committee is thinking actively about this.
>
> |  Personally, I think AMP was the right thing to do, but I don't think FTP was
> |  the right thing.
>
> These make good examples to motivate future changes to our process.  But in the end FTP was subject to a pretty broad deliberative process, precisely along the lines that Geoff suggests above.  We had two clearly-articulated alternatives, a discrete call for opinions broadcast to every Haskell channel we could find, a decent interval for people to respond, and (as it turned out) a very clear preponderance of opinion in one direction.  In a big community, even a broad consultation may yield a result that some think is ill-advised.  That's part of the joyful burden of being a big community.
>
> Let's look forward, not back.  I think we can do better in future than we have done in the past.  I don't think we can hope for unanimity, but I think we can reasonably seek
>
>  * transparency;
>  * clarity about what decisions are on the table;
>  * broad consultation about decisions that affect
>     a broad constituency; and
>  * a decent opportunity to debate them without having
>     to be involved in massive email threads.  Let's try do to that.
>
> Simon
>
> PS: For what it's worth I'm less keen on Geoff's other proposal:
>
> |  Proposal 3: A decision regarding any proposal that significantly affects
> |  backwards compatibility is within the purview of the Haskell Prime
> |  Committee, not the Core Libraries Committee.
>
> *Precisely* the same issues will arise whether it's CLC or HPC.  And the HPC is going to be jolly busy with language issues. Moving the question from one group to another risks avoiding the issue rather than addressing it.

For the record, I am also not sure Proposal 3 is a good idea :)

However, I do think we could clarify what the respective
responsibilities of the core libraries committee and Haskell Prime
committees are.

One possible choice is that the core libraries committee is responsible
for changes to the core libraries that do not affect libraries in the
report. It is meant to be nimble, able to quickly deal with the large
volume of library changes that do not impact backwards compatibility.

In this scenario, the Haskell Prime committee, using a longer
deliberative process, would consider the more impactful library changes
and batch them up into new reports.

You are absolutely correct that moving the question to the Haskell Prime
committee risks pushing the issue around. The idea behind the separation
outlined above is to reduce the treadmill; the two bodies use different
processes, with different time frames, to arrive at decisions. Some
library decisions may deserve a longer deliberative process.

Cheers,
Geoff
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Re: [Haskell-cafe] Committee M.O. Change Proposals

Edward Kmett-2
In reply to this post by Geoffrey Mainland
The committee was formed from a pool of suggestions supplied to SPJ that represented a fairly wide cross-section of the community.

Simon initially offered both myself and Johan Tibell the role of co-chairs. Johan ultimately declined.

In the end, putting perhaps too simple a spin on it, the initial committee was selected: Michael Snoyman for commercial interest, Mark Lentczner representing the needs of the Platform and implementation concerns, Brent Yorgey on the theory side, Doug Beardsley representing practitioners, Joachim Breitner had expressed interest in working on split base, which at the time was a much more active concern, Dan Doel represented a decent balance of theory and practice.

Since then we had two slots open up on the committee, and precisely two self-nominations to fill them, which rather simplified the selection process. Brent and Doug rotated out and Eric Mertens and Luite Stegeman rotated in.

Technically, yes, we are self-selected going forward, based on the precedent of the haskell.org committee and haskell-prime committees, but you'll note this hasn't actually been a factor yet as there hasn't been any decision point reached where that has affected a membership decision.

-Edward

On Wed, Oct 21, 2015 at 8:31 AM, Geoffrey Mainland <[hidden email]> wrote:
On 10/21/2015 07:55 AM, Herbert Valerio Riedel wrote:
> Hello, > > On 2015-10-21 at 02:39:57 +0200, Geoffrey Mainland wrote: > > [...]
> >> In effect, only those who actively follow the libraries list have
had a >> voice in these decisions. Maybe that is what the community
wants. I hope >> not. How then can people like me (and Henrik and
Graham) have a say >> without committing to actively following the
libraries list? >>  >> We have a method to solve this: elected
representatives. Right now the >> Core Libraries Committee elects its
own members; perhaps it is time for >> that to change. > > [...] > >>
Proposal 1: Move to community election of the members of the Core >>
Libraries Committee. Yes, I know this would have its own issues. > > How
exactly do public elections of representatives address the problem >
that some people feel left out? Have you considered nominating yourself
> or somebody else you have confidence in for the core libraries >
committee? You'd still have to find somebody to represent your >
interests, regardless of whether the committee is self-elected or >
direct-elected. > > Here's some food for thought regarding language
design by voting or its > indirect form via a directly elected language
committee: > > Back in February there was a large-scale survey which
resulted (see [2] > for more details) in a rather unequivocal 4:1
majority *for* going > through with the otherwise controversial FTP
implementation. If the > community elections would result in a similar
spirit, you'd could easily > end up with a similarly 4:1 pro-change
biased committee. Would you > consider that a well balanced committee
formation?

Thanks, all good points.

It is quite possible that direct elections would produce the exact same
committee. I wouldn't see that as a negative outcome at all! At least
that committee would have been put in place by direct election; I would
see that as strengthening their mandate.

I am very much aware of the February survey. I wonder if Proposal 2, had
it been in place at the time, would have increased participation in the
survey.

The recent kerfuffle has caught the attention of many people who don't
normally follow the libraries list. Proposal 1 is an attempt to give
them a voice. Yes, they would still need to find a candidate to
represent their interests. If we moved to direct elections, I would
consider running. However, my preference is that Proposal 3 go through
in some form, in which case my main concern would be the Haskell Prime
committee, and unfortunately nominations for that committee have already
closed.

>> Proposal 2: After a suitable period of discussion on the libraries list, >> the Core Libraries Committee will summarize the arguments for and >>
against a proposal and post it, along with a (justified) preliminary >>
decision, to a low-traffic, announce-only email list. After another >>
suitable period of discussion, they will issue a final decision. What is
>> a suitable period of time? Perhaps that depends on the properties of
the >> proposal, such as whether it breaks backwards compatibility. > >
That generally sounds like a good compromise, if this actually helps >
reaching the otherwise unreachable parts of the community and have their
> voices heard.

My hope is that a low-volume mailing list would indeed reach a wider
audience.

>> Proposal 3: A decision regarding any proposal that significantly affects >> backwards compatibility is within the purview of the Haskell Prime
>> Committee, not the Core Libraries Committee. > > I don't see how that
would change much. The prior Haskell Prime > Committee has been
traditionally self-elected as well. So it's just the > label of the
committee you'd swap out. > > In the recent call of nominations[1] for
Haskell Prime, the stated area > of work for the new nominations was to
take care of the *language* part, > because that's what we are lacking
the workforce for. > > Since its creation for the very purpose of
watching over the core > libraries, the core-libraries-committee has
been almost exclusively busy > with evaluating and deciding about
changes to the `base` library and > overseeing their implementation.
Transferring this huge workload to the > new Haskell Prime committee
members who have already their hands full > with revising the language
part would IMO just achieve to reduce the > effectiveness of the
upcoming Haskell Prime committee, and therefore > increase the risk of
failure in producing an adequate new Haskell Report > revision.

My understanding is that much of the work of the core libraries
committee does not "significantly affect backwards compatibility," at
least not to the extent that MRP does. If this is the case, the bulk of
their workload would not be transferred to the new Haskell Prime
committee. Is my understanding incorrect?

The intent of Proposal 3 was to transfer only a small fraction of the
issues that come before the core libraries committee to the Haskell
Prime committee. In any case, we would certainly need to clarify what
"significantly affects backwards compatibility" means.

Perhaps we should consider direct elections for the Haskell Prime
committee as well as changing their mandate to include some subset of
the changes proposed to libraries covered by the Haskell Report. My
understanding of the current state of affairs is that the Haskell Prime
committee is charged with producing a new report, but the core libraries
committee is in charge of the library part of that report. Is that
correct?

Cheers,
Geoff

> Regards, >   H.V.Riedel > >  [1]:
https://mail.haskell.org/pipermail/haskell-prime/2015-September/003936.html
>  [2]:
https://mail.haskell.org/pipermail/haskell-cafe/2015-February/118336.html


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Re: [Haskell-cafe] Committee M.O. Change Proposals

Geoffrey Mainland
Thanks for the background, Edward.

I don't mean to question the composition of the committee, only to start
a discussion about how the community might handle the selection process
going forward. I apologize if I was not clear about that. As I said
below, if a direct vote resulted in the same committee we would have had
under the current system, I would consider that a success!

We may also see a larger nomination pool in the future :)

Cheers,
Geoff

On 10/21/2015 03:54 PM, Edward Kmett wrote:

> The committee was formed from a pool of suggestions supplied to SPJ
> that represented a fairly wide cross-section of the community.
>
> Simon initially offered both myself and Johan Tibell the role of
> co-chairs. Johan ultimately declined.
>
> In the end, putting perhaps too simple a spin on it, the initial
> committee was selected: Michael Snoyman for commercial interest, Mark
> Lentczner representing the needs of the Platform and implementation
> concerns, Brent Yorgey on the theory side, Doug Beardsley representing
> practitioners, Joachim Breitner had expressed interest in working on
> split base, which at the time was a much more active concern, Dan Doel
> represented a decent balance of theory and practice.
>
> Since then we had two slots open up on the committee, and precisely
> two self-nominations to fill them, which rather simplified the
> selection process. Brent and Doug rotated out and Eric Mertens and
> Luite Stegeman rotated in.
>
> Technically, yes, we are self-selected going forward, based on the
> precedent of the haskell.org <http://haskell.org> committee and
> haskell-prime committees, but you'll note this hasn't actually been a
> factor yet as there hasn't been any decision point reached where that
> has affected a membership decision.
>
> -Edward
>
> On Wed, Oct 21, 2015 at 8:31 AM, Geoffrey Mainland
> <[hidden email] <mailto:[hidden email]>> wrote:
>
>     On 10/21/2015 07:55 AM, Herbert Valerio Riedel wrote:
>     > Hello, > > On 2015-10-21 at 02:39:57 +0200, Geoffrey Mainland
>     wrote: > > [...]
>     > >> In effect, only those who actively follow the libraries list have
>     had a >> voice in these decisions. Maybe that is what the community
>     wants. I hope >> not. How then can people like me (and Henrik and
>     Graham) have a say >> without committing to actively following the
>     libraries list? >>  >> We have a method to solve this: elected
>     representatives. Right now the >> Core Libraries Committee elects its
>     own members; perhaps it is time for >> that to change. > > [...] > >>
>     Proposal 1: Move to community election of the members of the Core >>
>     Libraries Committee. Yes, I know this would have its own issues. >
>     > How
>     exactly do public elections of representatives address the problem >
>     that some people feel left out? Have you considered nominating
>     yourself
>     > or somebody else you have confidence in for the core libraries >
>     committee? You'd still have to find somebody to represent your >
>     interests, regardless of whether the committee is self-elected or >
>     direct-elected. > > Here's some food for thought regarding language
>     design by voting or its > indirect form via a directly elected
>     language
>     committee: > > Back in February there was a large-scale survey which
>     resulted (see [2] > for more details) in a rather unequivocal 4:1
>     majority *for* going > through with the otherwise controversial FTP
>     implementation. If the > community elections would result in a similar
>     spirit, you'd could easily > end up with a similarly 4:1 pro-change
>     biased committee. Would you > consider that a well balanced committee
>     formation?
>
>     Thanks, all good points.
>
>     It is quite possible that direct elections would produce the exact
>     same
>     committee. I wouldn't see that as a negative outcome at all! At least
>     that committee would have been put in place by direct election; I
>     would
>     see that as strengthening their mandate.
>
>     I am very much aware of the February survey. I wonder if Proposal
>     2, had
>     it been in place at the time, would have increased participation
>     in the
>     survey.
>
>     The recent kerfuffle has caught the attention of many people who don't
>     normally follow the libraries list. Proposal 1 is an attempt to give
>     them a voice. Yes, they would still need to find a candidate to
>     represent their interests. If we moved to direct elections, I would
>     consider running. However, my preference is that Proposal 3 go through
>     in some form, in which case my main concern would be the Haskell Prime
>     committee, and unfortunately nominations for that committee have
>     already
>     closed.
>
>     >> Proposal 2: After a suitable period of discussion on the
>     libraries list, >> the Core Libraries Committee will summarize the
>     arguments for and >>
>     against a proposal and post it, along with a (justified)
>     preliminary >>
>     decision, to a low-traffic, announce-only email list. After another >>
>     suitable period of discussion, they will issue a final decision.
>     What is
>     >> a suitable period of time? Perhaps that depends on the
>     properties of
>     the >> proposal, such as whether it breaks backwards
>     compatibility. > >
>     That generally sounds like a good compromise, if this actually helps >
>     reaching the otherwise unreachable parts of the community and have
>     their
>     > voices heard.
>
>     My hope is that a low-volume mailing list would indeed reach a wider
>     audience.
>
>     >> Proposal 3: A decision regarding any proposal that
>     significantly affects >> backwards compatibility is within the
>     purview of the Haskell Prime
>     >> Committee, not the Core Libraries Committee. > > I don't see
>     how that
>     would change much. The prior Haskell Prime > Committee has been
>     traditionally self-elected as well. So it's just the > label of the
>     committee you'd swap out. > > In the recent call of nominations[1] for
>     Haskell Prime, the stated area > of work for the new nominations
>     was to
>     take care of the *language* part, > because that's what we are lacking
>     the workforce for. > > Since its creation for the very purpose of
>     watching over the core > libraries, the core-libraries-committee has
>     been almost exclusively busy > with evaluating and deciding about
>     changes to the `base` library and > overseeing their implementation.
>     Transferring this huge workload to the > new Haskell Prime committee
>     members who have already their hands full > with revising the language
>     part would IMO just achieve to reduce the > effectiveness of the
>     upcoming Haskell Prime committee, and therefore > increase the risk of
>     failure in producing an adequate new Haskell Report > revision.
>
>     My understanding is that much of the work of the core libraries
>     committee does not "significantly affect backwards compatibility," at
>     least not to the extent that MRP does. If this is the case, the
>     bulk of
>     their workload would not be transferred to the new Haskell Prime
>     committee. Is my understanding incorrect?
>
>     The intent of Proposal 3 was to transfer only a small fraction of the
>     issues that come before the core libraries committee to the Haskell
>     Prime committee. In any case, we would certainly need to clarify what
>     "significantly affects backwards compatibility" means.
>
>     Perhaps we should consider direct elections for the Haskell Prime
>     committee as well as changing their mandate to include some subset of
>     the changes proposed to libraries covered by the Haskell Report. My
>     understanding of the current state of affairs is that the Haskell
>     Prime
>     committee is charged with producing a new report, but the core
>     libraries
>     committee is in charge of the library part of that report. Is that
>     correct?
>
>     Cheers,
>     Geoff
>
>     > Regards, >   H.V.Riedel > >  [1]:
>     https://mail.haskell.org/pipermail/haskell-prime/2015-September/003936.html
>     >  [2]:
>     https://mail.haskell.org/pipermail/haskell-cafe/2015-February/118336.html
>
>

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Re: Breaking Changes and Long Term Support Haskell

Dan Doel
In reply to this post by Geoffrey Mainland
Hello,

I'm Dan Doel. I'm on the core libraries committee (though I'm speaking
only for myself). As I recall, one of the reasons I got tapped for it
was due to my having some historical knowledge about Haskell; not
because I was there, but because I've gone back and looked at some old
reports and whatnot (and sometimes think they're better than what we
have now).

But, I was around (of course) when the core libraries committee
started up, so perhaps I can play the role of historian for this as
well.

The reason the committee exists is because a couple years ago, people
brought up the ideas that were finally realized in the
Applicative-Monad proposal and the Foldable-Traversable proposal. A
lot of people weighed in saying they thought they were a good idea,
and significantly fewer people weighed in saying they thought that it
shouldn't happen for various reasons---roughly the same things that
people are still bringing up about these proposals.

This wasn't the first time that happened, either. I think it was
widely agreed among most users that Functor should be a superclass of
Monad since I started learning Haskell around 10 years ago. And once
Applicative was introduced, it was agreed that that should go in the
middle of the two. But it appeared that it would never happen, despite
a significant majority thinking it should, because no one wanted to do
anything without pretty much unanimous consent.

So, one question that got raised is: why should this majority of
people even use Haskell/GHC anymore? Why shouldn't they start using
some other language that will let them change 15-year-old mistakes, or
adapt to ideas that weren't even available at that time (but are still
fairly old and established, all things considered). And the answer was
that there should be some body empowered to decide to move forward
with these ideas, even if there is some dissent. And frankly, it
wasn't going to be the prime committee, because it hadn't shown any
activity in something like 3 years at the time, and even when it was
active, it didn't make anywhere near the sort of changes that were
being discussed.

And the kicker to me is, many things that people are complaining about
again (e.g. the FTP) were the very things that the committee was
established to execute. I don't think we had a formal vote on that
proposal, because we didn't need to. Our existence was in part to
execute that proposal (and AMP). And then a year ago, when it was
finally time to release the changes, there was another ruckus. And we
still didn't have a CLC vote on the matter. What we did was conduct a
community poll, and then SPJ reviewed the submissions. But I don't
mean to pass the buck to him, because I'm pretty sure he was worried
that we were crazy, and overstepping our bounds. Just, the results of
the survey were sufficient for him to not overrule us.

So my point is this: there seems to be some sentiment that the core
libraries committee is unsound, and making bad decisions. But the
complaints are mostly not even about actual decisions we made (aside
from maybe Lennart Augustsson's, where he is unhappy with details of
the FTP that you can blame on us, but were designed to break the least
code, instead of being the most elegant; if we had pleased him more,
we would have pleased others less). They are about the reasons for
founding the committee in the first place. You can blame us, if you
like, because I think it's certain that we would have approved them if
we had formally voted. We just didn't even need to do so.

Forgive me if I'm wrong, but suggestions that these decisions should
have been deferred to a Haskell Prime committee mean, to me, that the
hope is that they would have been rejected. That the Haskell Prime
committee should have just vetoed these proposals that something like
80% or more of practicing Haskell users (as far as we can tell) wanted
for years before they finally happened. That the Haskell Prime
committee should be responsible for enforcing the very status quo that
led to the CLC in the first place, where proposals with broad support
but minority dissent never pass for various core modules.

If this is the case, then one could simply repose the earlier
question: why should most of these people stick around to obey by the
Haskell Prime committee's pronouncements, instead of getting to work
on a language that incorporates their input?

And if it isn't, then I don't ultimately understand what the
complaints are. We try to accomplish the (large) changes in a manner
that allows transition via refactoring over multiple versions (and as
I mentioned earlier, some complaints are that we compromised _too
much_ for this). And in light of the more recent complaints, it's even
been decided that our time frames should be longer. Rolling up changes
into a report just seems like it makes transitions less smooth. Unless
the idea is to make GHC capable of switching out entire base library
sets; but someone has to implement that, and once you have it, it
makes the report specifications _less_ essential.

Anyhow, that's my history lesson. Take it as you (all) will.

Cheers,
-- Dan

On Wed, Oct 21, 2015 at 10:43 AM, Geoffrey Mainland
<[hidden email]> wrote:

> On 10/21/2015 07:30 AM, Simon Peyton Jones wrote:
>> Friends
>>
>> I think it's good for us to debate the question of how we should balance innovation against change; and how we should make those decisions in future.  Geoff's message had some good ideas, especially this bit:
>>
>> |  Proposal 2: After a suitable period of discussion on the libraries list, the
>> |  Core Libraries Committee will summarize the arguments for and against a
>> |  proposal and post it, along with a (justified) preliminary decision, to a
>> |  low-traffic, announce-only email list. After another suitable period of
>> |  discussion, they will issue a final decision. What is a suitable period of
>> |  time? Perhaps that depends on the properties of the proposal, such as
>> |  whether it breaks backwards compatibility.
>>
>> Identifying major changes to the libraries, and having a better publicised, more RFC-like process for deliberating them, would be a good thing.  I believe that the Core Libraries committee is thinking actively about this.
>>
>> |  Personally, I think AMP was the right thing to do, but I don't think FTP was
>> |  the right thing.
>>
>> These make good examples to motivate future changes to our process.  But in the end FTP was subject to a pretty broad deliberative process, precisely along the lines that Geoff suggests above.  We had two clearly-articulated alternatives, a discrete call for opinions broadcast to every Haskell channel we could find, a decent interval for people to respond, and (as it turned out) a very clear preponderance of opinion in one direction.  In a big community, even a broad consultation may yield a result that some think is ill-advised.  That's part of the joyful burden of being a big community.
>>
>> Let's look forward, not back.  I think we can do better in future than we have done in the past.  I don't think we can hope for unanimity, but I think we can reasonably seek
>>
>>  * transparency;
>>  * clarity about what decisions are on the table;
>>  * broad consultation about decisions that affect
>>     a broad constituency; and
>>  * a decent opportunity to debate them without having
>>     to be involved in massive email threads.  Let's try do to that.
>>
>> Simon
>>
>> PS: For what it's worth I'm less keen on Geoff's other proposal:
>>
>> |  Proposal 3: A decision regarding any proposal that significantly affects
>> |  backwards compatibility is within the purview of the Haskell Prime
>> |  Committee, not the Core Libraries Committee.
>>
>> *Precisely* the same issues will arise whether it's CLC or HPC.  And the HPC is going to be jolly busy with language issues. Moving the question from one group to another risks avoiding the issue rather than addressing it.
>
> For the record, I am also not sure Proposal 3 is a good idea :)
>
> However, I do think we could clarify what the respective
> responsibilities of the core libraries committee and Haskell Prime
> committees are.
>
> One possible choice is that the core libraries committee is responsible
> for changes to the core libraries that do not affect libraries in the
> report. It is meant to be nimble, able to quickly deal with the large
> volume of library changes that do not impact backwards compatibility.
>
> In this scenario, the Haskell Prime committee, using a longer
> deliberative process, would consider the more impactful library changes
> and batch them up into new reports.
>
> You are absolutely correct that moving the question to the Haskell Prime
> committee risks pushing the issue around. The idea behind the separation
> outlined above is to reduce the treadmill; the two bodies use different
> processes, with different time frames, to arrive at decisions. Some
> library decisions may deserve a longer deliberative process.
>
> Cheers,
> Geoff
> _______________________________________________
> Libraries mailing list
> [hidden email]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
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Re: Breaking Changes and Long Term Support Haskell

Carter Schonwald
Well said!

I do have a small worry that the longer roll out window will be harder to manage given that every thing is done by (outstanding) volunteers.  But maybe the answer there is that ghc should do major version releases more frequently :), eg every 9 months instead of every 12! 😀

On Wednesday, October 21, 2015, Dan Doel <[hidden email]> wrote:
Hello,

I'm Dan Doel. I'm on the core libraries committee (though I'm speaking
only for myself). As I recall, one of the reasons I got tapped for it
was due to my having some historical knowledge about Haskell; not
because I was there, but because I've gone back and looked at some old
reports and whatnot (and sometimes think they're better than what we
have now).

But, I was around (of course) when the core libraries committee
started up, so perhaps I can play the role of historian for this as
well.

The reason the committee exists is because a couple years ago, people
brought up the ideas that were finally realized in the
Applicative-Monad proposal and the Foldable-Traversable proposal. A
lot of people weighed in saying they thought they were a good idea,
and significantly fewer people weighed in saying they thought that it
shouldn't happen for various reasons---roughly the same things that
people are still bringing up about these proposals.

This wasn't the first time that happened, either. I think it was
widely agreed among most users that Functor should be a superclass of
Monad since I started learning Haskell around 10 years ago. And once
Applicative was introduced, it was agreed that that should go in the
middle of the two. But it appeared that it would never happen, despite
a significant majority thinking it should, because no one wanted to do
anything without pretty much unanimous consent.

So, one question that got raised is: why should this majority of
people even use Haskell/GHC anymore? Why shouldn't they start using
some other language that will let them change 15-year-old mistakes, or
adapt to ideas that weren't even available at that time (but are still
fairly old and established, all things considered). And the answer was
that there should be some body empowered to decide to move forward
with these ideas, even if there is some dissent. And frankly, it
wasn't going to be the prime committee, because it hadn't shown any
activity in something like 3 years at the time, and even when it was
active, it didn't make anywhere near the sort of changes that were
being discussed.

And the kicker to me is, many things that people are complaining about
again (e.g. the FTP) were the very things that the committee was
established to execute. I don't think we had a formal vote on that
proposal, because we didn't need to. Our existence was in part to
execute that proposal (and AMP). And then a year ago, when it was
finally time to release the changes, there was another ruckus. And we
still didn't have a CLC vote on the matter. What we did was conduct a
community poll, and then SPJ reviewed the submissions. But I don't
mean to pass the buck to him, because I'm pretty sure he was worried
that we were crazy, and overstepping our bounds. Just, the results of
the survey were sufficient for him to not overrule us.

So my point is this: there seems to be some sentiment that the core
libraries committee is unsound, and making bad decisions. But the
complaints are mostly not even about actual decisions we made (aside
from maybe Lennart Augustsson's, where he is unhappy with details of
the FTP that you can blame on us, but were designed to break the least
code, instead of being the most elegant; if we had pleased him more,
we would have pleased others less). They are about the reasons for
founding the committee in the first place. You can blame us, if you
like, because I think it's certain that we would have approved them if
we had formally voted. We just didn't even need to do so.

Forgive me if I'm wrong, but suggestions that these decisions should
have been deferred to a Haskell Prime committee mean, to me, that the
hope is that they would have been rejected. That the Haskell Prime
committee should have just vetoed these proposals that something like
80% or more of practicing Haskell users (as far as we can tell) wanted
for years before they finally happened. That the Haskell Prime
committee should be responsible for enforcing the very status quo that
led to the CLC in the first place, where proposals with broad support
but minority dissent never pass for various core modules.

If this is the case, then one could simply repose the earlier
question: why should most of these people stick around to obey by the
Haskell Prime committee's pronouncements, instead of getting to work
on a language that incorporates their input?

And if it isn't, then I don't ultimately understand what the
complaints are. We try to accomplish the (large) changes in a manner
that allows transition via refactoring over multiple versions (and as
I mentioned earlier, some complaints are that we compromised _too
much_ for this). And in light of the more recent complaints, it's even
been decided that our time frames should be longer. Rolling up changes
into a report just seems like it makes transitions less smooth. Unless
the idea is to make GHC capable of switching out entire base library
sets; but someone has to implement that, and once you have it, it
makes the report specifications _less_ essential.

Anyhow, that's my history lesson. Take it as you (all) will.

Cheers,
-- Dan

On Wed, Oct 21, 2015 at 10:43 AM, Geoffrey Mainland
<<a href="javascript:;" onclick="_e(event, &#39;cvml&#39;, &#39;mainland@apeiron.net&#39;)">mainland@...> wrote:
> On 10/21/2015 07:30 AM, Simon Peyton Jones wrote:
>> Friends
>>
>> I think it's good for us to debate the question of how we should balance innovation against change; and how we should make those decisions in future.  Geoff's message had some good ideas, especially this bit:
>>
>> |  Proposal 2: After a suitable period of discussion on the libraries list, the
>> |  Core Libraries Committee will summarize the arguments for and against a
>> |  proposal and post it, along with a (justified) preliminary decision, to a
>> |  low-traffic, announce-only email list. After another suitable period of
>> |  discussion, they will issue a final decision. What is a suitable period of
>> |  time? Perhaps that depends on the properties of the proposal, such as
>> |  whether it breaks backwards compatibility.
>>
>> Identifying major changes to the libraries, and having a better publicised, more RFC-like process for deliberating them, would be a good thing.  I believe that the Core Libraries committee is thinking actively about this.
>>
>> |  Personally, I think AMP was the right thing to do, but I don't think FTP was
>> |  the right thing.
>>
>> These make good examples to motivate future changes to our process.  But in the end FTP was subject to a pretty broad deliberative process, precisely along the lines that Geoff suggests above.  We had two clearly-articulated alternatives, a discrete call for opinions broadcast to every Haskell channel we could find, a decent interval for people to respond, and (as it turned out) a very clear preponderance of opinion in one direction.  In a big community, even a broad consultation may yield a result that some think is ill-advised.  That's part of the joyful burden of being a big community.
>>
>> Let's look forward, not back.  I think we can do better in future than we have done in the past.  I don't think we can hope for unanimity, but I think we can reasonably seek
>>
>>  * transparency;
>>  * clarity about what decisions are on the table;
>>  * broad consultation about decisions that affect
>>     a broad constituency; and
>>  * a decent opportunity to debate them without having
>>     to be involved in massive email threads.  Let's try do to that.
>>
>> Simon
>>
>> PS: For what it's worth I'm less keen on Geoff's other proposal:
>>
>> |  Proposal 3: A decision regarding any proposal that significantly affects
>> |  backwards compatibility is within the purview of the Haskell Prime
>> |  Committee, not the Core Libraries Committee.
>>
>> *Precisely* the same issues will arise whether it's CLC or HPC.  And the HPC is going to be jolly busy with language issues. Moving the question from one group to another risks avoiding the issue rather than addressing it.
>
> For the record, I am also not sure Proposal 3 is a good idea :)
>
> However, I do think we could clarify what the respective
> responsibilities of the core libraries committee and Haskell Prime
> committees are.
>
> One possible choice is that the core libraries committee is responsible
> for changes to the core libraries that do not affect libraries in the
> report. It is meant to be nimble, able to quickly deal with the large
> volume of library changes that do not impact backwards compatibility.
>
> In this scenario, the Haskell Prime committee, using a longer
> deliberative process, would consider the more impactful library changes
> and batch them up into new reports.
>
> You are absolutely correct that moving the question to the Haskell Prime
> committee risks pushing the issue around. The idea behind the separation
> outlined above is to reduce the treadmill; the two bodies use different
> processes, with different time frames, to arrive at decisions. Some
> library decisions may deserve a longer deliberative process.
>
> Cheers,
> Geoff
> _______________________________________________
> Libraries mailing list
> <a href="javascript:;" onclick="_e(event, &#39;cvml&#39;, &#39;Libraries@haskell.org&#39;)">Libraries@...
> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
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RE: Breaking Changes and Long Term Support Haskell

Simon Peyton Jones
In reply to this post by Dan Doel
While we are here, let me say

  A BIG THANK YOU TO THE CORE LIBRARIES COMMITTEE

Library design has a lot of detail, and a lot of competing priorities.  I am personally very grateful to the CLC for the work they put into this. Like many crucial tasks it's one that often seems to attract more complaints than thanks, but they are doing us all a huge service, and at significant cost in terms of their most precious and inelastic commodity: their personal time.

Remember, as Dan says, before the CLC we no process whatsoever for library evolution... various people made various patches, and there was no way of getting anything substantial done.  So we are far far further on than before.

Still not perfect, as my last post said. But still: THANK YOU.

Simon

| -----Original Message-----
| From: Dan Doel [mailto:[hidden email]]
| Sent: 21 October 2015 22:23
| To: Geoffrey Mainland
| Cc: Simon Peyton Jones; Augustsson, Lennart; Henrik Nilsson; haskell-
| [hidden email] List; Haskell Libraries
| Subject: Re: Breaking Changes and Long Term Support Haskell
|
| Hello,
|
| I'm Dan Doel. I'm on the core libraries committee (though I'm speaking
| only for myself). As I recall, one of the reasons I got tapped for it
| was due to my having some historical knowledge about Haskell; not
| because I was there, but because I've gone back and looked at some old
| reports and whatnot (and sometimes think they're better than what we
| have now).
|
| But, I was around (of course) when the core libraries committee
| started up, so perhaps I can play the role of historian for this as
| well.
|
| The reason the committee exists is because a couple years ago, people
| brought up the ideas that were finally realized in the
| Applicative-Monad proposal and the Foldable-Traversable proposal. A
| lot of people weighed in saying they thought they were a good idea,
| and significantly fewer people weighed in saying they thought that it
| shouldn't happen for various reasons---roughly the same things that
| people are still bringing up about these proposals.
|
| This wasn't the first time that happened, either. I think it was
| widely agreed among most users that Functor should be a superclass of
| Monad since I started learning Haskell around 10 years ago. And once
| Applicative was introduced, it was agreed that that should go in the
| middle of the two. But it appeared that it would never happen, despite
| a significant majority thinking it should, because no one wanted to do
| anything without pretty much unanimous consent.
|
| So, one question that got raised is: why should this majority of
| people even use Haskell/GHC anymore? Why shouldn't they start using
| some other language that will let them change 15-year-old mistakes, or
| adapt to ideas that weren't even available at that time (but are still
| fairly old and established, all things considered). And the answer was
| that there should be some body empowered to decide to move forward
| with these ideas, even if there is some dissent. And frankly, it
| wasn't going to be the prime committee, because it hadn't shown any
| activity in something like 3 years at the time, and even when it was
| active, it didn't make anywhere near the sort of changes that were
| being discussed.
|
| And the kicker to me is, many things that people are complaining about
| again (e.g. the FTP) were the very things that the committee was
| established to execute. I don't think we had a formal vote on that
| proposal, because we didn't need to. Our existence was in part to
| execute that proposal (and AMP). And then a year ago, when it was
| finally time to release the changes, there was another ruckus. And we
| still didn't have a CLC vote on the matter. What we did was conduct a
| community poll, and then SPJ reviewed the submissions. But I don't
| mean to pass the buck to him, because I'm pretty sure he was worried
| that we were crazy, and overstepping our bounds. Just, the results of
| the survey were sufficient for him to not overrule us.
|
| So my point is this: there seems to be some sentiment that the core
| libraries committee is unsound, and making bad decisions. But the
| complaints are mostly not even about actual decisions we made (aside
| from maybe Lennart Augustsson's, where he is unhappy with details of
| the FTP that you can blame on us, but were designed to break the least
| code, instead of being the most elegant; if we had pleased him more,
| we would have pleased others less). They are about the reasons for
| founding the committee in the first place. You can blame us, if you
| like, because I think it's certain that we would have approved them if
| we had formally voted. We just didn't even need to do so.
|
| Forgive me if I'm wrong, but suggestions that these decisions should
| have been deferred to a Haskell Prime committee mean, to me, that the
| hope is that they would have been rejected. That the Haskell Prime
| committee should have just vetoed these proposals that something like
| 80% or more of practicing Haskell users (as far as we can tell) wanted
| for years before they finally happened. That the Haskell Prime
| committee should be responsible for enforcing the very status quo that
| led to the CLC in the first place, where proposals with broad support
| but minority dissent never pass for various core modules.
|
| If this is the case, then one could simply repose the earlier
| question: why should most of these people stick around to obey by the
| Haskell Prime committee's pronouncements, instead of getting to work
| on a language that incorporates their input?
|
| And if it isn't, then I don't ultimately understand what the
| complaints are. We try to accomplish the (large) changes in a manner
| that allows transition via refactoring over multiple versions (and as
| I mentioned earlier, some complaints are that we compromised _too
| much_ for this). And in light of the more recent complaints, it's even
| been decided that our time frames should be longer. Rolling up changes
| into a report just seems like it makes transitions less smooth. Unless
| the idea is to make GHC capable of switching out entire base library
| sets; but someone has to implement that, and once you have it, it
| makes the report specifications _less_ essential.
|
| Anyhow, that's my history lesson. Take it as you (all) will.
|
| Cheers,
| -- Dan
|
| On Wed, Oct 21, 2015 at 10:43 AM, Geoffrey Mainland
| <[hidden email]> wrote:
| > On 10/21/2015 07:30 AM, Simon Peyton Jones wrote:
| >> Friends
| >>
| >> I think it's good for us to debate the question of how we should
| balance innovation against change; and how we should make those decisions
| in future.  Geoff's message had some good ideas, especially this bit:
| >>
| >> |  Proposal 2: After a suitable period of discussion on the libraries
| list, the
| >> |  Core Libraries Committee will summarize the arguments for and
| against a
| >> |  proposal and post it, along with a (justified) preliminary decision,
| to a
| >> |  low-traffic, announce-only email list. After another suitable period
| of
| >> |  discussion, they will issue a final decision. What is a suitable
| period of
| >> |  time? Perhaps that depends on the properties of the proposal, such
| as
| >> |  whether it breaks backwards compatibility.
| >>
| >> Identifying major changes to the libraries, and having a better
| publicised, more RFC-like process for deliberating them, would be a good
| thing.  I believe that the Core Libraries committee is thinking actively
| about this.
| >>
| >> |  Personally, I think AMP was the right thing to do, but I don't think
| FTP was
| >> |  the right thing.
| >>
| >> These make good examples to motivate future changes to our process.
| But in the end FTP was subject to a pretty broad deliberative process,
| precisely along the lines that Geoff suggests above.  We had two clearly-
| articulated alternatives, a discrete call for opinions broadcast to every
| Haskell channel we could find, a decent interval for people to respond,
| and (as it turned out) a very clear preponderance of opinion in one
| direction.  In a big community, even a broad consultation may yield a
| result that some think is ill-advised.  That's part of the joyful burden
| of being a big community.
| >>
| >> Let's look forward, not back.  I think we can do better in future than
| we have done in the past.  I don't think we can hope for unanimity, but I
| think we can reasonably seek
| >>
| >>  * transparency;
| >>  * clarity about what decisions are on the table;
| >>  * broad consultation about decisions that affect
| >>     a broad constituency; and
| >>  * a decent opportunity to debate them without having
| >>     to be involved in massive email threads.  Let's try do to that.
| >>
| >> Simon
| >>
| >> PS: For what it's worth I'm less keen on Geoff's other proposal:
| >>
| >> |  Proposal 3: A decision regarding any proposal that significantly
| affects
| >> |  backwards compatibility is within the purview of the Haskell Prime
| >> |  Committee, not the Core Libraries Committee.
| >>
| >> *Precisely* the same issues will arise whether it's CLC or HPC.  And
| the HPC is going to be jolly busy with language issues. Moving the
| question from one group to another risks avoiding the issue rather than
| addressing it.
| >
| > For the record, I am also not sure Proposal 3 is a good idea :)
| >
| > However, I do think we could clarify what the respective
| > responsibilities of the core libraries committee and Haskell Prime
| > committees are.
| >
| > One possible choice is that the core libraries committee is responsible
| > for changes to the core libraries that do not affect libraries in the
| > report. It is meant to be nimble, able to quickly deal with the large
| > volume of library changes that do not impact backwards compatibility.
| >
| > In this scenario, the Haskell Prime committee, using a longer
| > deliberative process, would consider the more impactful library changes
| > and batch them up into new reports.
| >
| > You are absolutely correct that moving the question to the Haskell Prime
| > committee risks pushing the issue around. The idea behind the separation
| > outlined above is to reduce the treadmill; the two bodies use different
| > processes, with different time frames, to arrive at decisions. Some
| > library decisions may deserve a longer deliberative process.
| >
| > Cheers,
| > Geoff
| > _______________________________________________
| > Libraries mailing list
| > [hidden email]
| >
| https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fmail.haske
| ll.org%2fcgi-
| bin%2fmailman%2flistinfo%2flibraries&data=01%7c01%7csimonpj%40064d.mgd.mic
| rosoft.com%7c6e0a5cbb4f5541caf14108d2da5dc7f8%7c72f988bf86f141af91ab2d7cd0
| 11db47%7c1&sdata=zL3zfXigvfpvdXL%2bhWuGoQzUUhGp%2bg8ofO1tGaFzlvE%3d
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RE: Breaking Changes and Long Term Support Haskell

Simon Peyton Jones
In reply to this post by Geoffrey Mainland
| For the record, I am also not sure Proposal 3 is a good idea :)
|
| However, I do think we could clarify what the respective
| responsibilities of the core libraries committee and Haskell Prime
| committees are.

My instinct is this:
  Haskell Prime: language
  Core Libraries Committee: libraries

That seems simple.  If we try to move the largest and most challenging library design tasks from CLC to HP, I fear that we will overload the latter and devalue the former.

| You are absolutely correct that moving the question to the Haskell Prime
| committee risks pushing the issue around. The idea behind the separation
| outlined above is to reduce the treadmill; the two bodies use different
| processes, with different time frames, to arrive at decisions. Some
| library decisions may deserve a longer deliberative process.

I do agree that some library changes are far-reaching, and need a more deliberative process.  I think the CLC is in the process of developing such a process.  Moreover, I trust them to be able to tell the difference between low-impact and high-impact changes.

That said, as HP moves towards a new language Report, it would be good if CLC similarly moved towards a new libraries Report, so that there was a single unified document, just as we have had to date.

Simon


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Re: Breaking Changes and Long Term Support Haskell

Geoffrey Mainland
In reply to this post by Dan Doel
Hi Dan,

Thank you for the historical perspective.

I was careful not to criticize the committee. Instead, I made three
concrete proposals with the hope that they would help orient a conversation.

It sounds like you are not for proposal 3. How about the other two?

My original email stated my underlying concern: we are losing valuable
members of the community not because of the technical decisions that are
being made, but because of the process by which they are being made.
That concern is what drove my proposals. It is perfectly valid to think
that that loss was the inevitable price of progress, but that is not my
view.

Cheers,
Geoff

On 10/21/15 5:22 PM, Dan Doel wrote:

> Hello,
>
> I'm Dan Doel. I'm on the core libraries committee (though I'm speaking
> only for myself). As I recall, one of the reasons I got tapped for it
> was due to my having some historical knowledge about Haskell; not
> because I was there, but because I've gone back and looked at some old
> reports and whatnot (and sometimes think they're better than what we
> have now).
>
> But, I was around (of course) when the core libraries committee
> started up, so perhaps I can play the role of historian for this as
> well.
>
> The reason the committee exists is because a couple years ago, people
> brought up the ideas that were finally realized in the
> Applicative-Monad proposal and the Foldable-Traversable proposal. A
> lot of people weighed in saying they thought they were a good idea,
> and significantly fewer people weighed in saying they thought that it
> shouldn't happen for various reasons---roughly the same things that
> people are still bringing up about these proposals.
>
> This wasn't the first time that happened, either. I think it was
> widely agreed among most users that Functor should be a superclass of
> Monad since I started learning Haskell around 10 years ago. And once
> Applicative was introduced, it was agreed that that should go in the
> middle of the two. But it appeared that it would never happen, despite
> a significant majority thinking it should, because no one wanted to do
> anything without pretty much unanimous consent.
>
> So, one question that got raised is: why should this majority of
> people even use Haskell/GHC anymore? Why shouldn't they start using
> some other language that will let them change 15-year-old mistakes, or
> adapt to ideas that weren't even available at that time (but are still
> fairly old and established, all things considered). And the answer was
> that there should be some body empowered to decide to move forward
> with these ideas, even if there is some dissent. And frankly, it
> wasn't going to be the prime committee, because it hadn't shown any
> activity in something like 3 years at the time, and even when it was
> active, it didn't make anywhere near the sort of changes that were
> being discussed.
>
> And the kicker to me is, many things that people are complaining about
> again (e.g. the FTP) were the very things that the committee was
> established to execute. I don't think we had a formal vote on that
> proposal, because we didn't need to. Our existence was in part to
> execute that proposal (and AMP). And then a year ago, when it was
> finally time to release the changes, there was another ruckus. And we
> still didn't have a CLC vote on the matter. What we did was conduct a
> community poll, and then SPJ reviewed the submissions. But I don't
> mean to pass the buck to him, because I'm pretty sure he was worried
> that we were crazy, and overstepping our bounds. Just, the results of
> the survey were sufficient for him to not overrule us.
>
> So my point is this: there seems to be some sentiment that the core
> libraries committee is unsound, and making bad decisions. But the
> complaints are mostly not even about actual decisions we made (aside
> from maybe Lennart Augustsson's, where he is unhappy with details of
> the FTP that you can blame on us, but were designed to break the least
> code, instead of being the most elegant; if we had pleased him more,
> we would have pleased others less). They are about the reasons for
> founding the committee in the first place. You can blame us, if you
> like, because I think it's certain that we would have approved them if
> we had formally voted. We just didn't even need to do so.
>
> Forgive me if I'm wrong, but suggestions that these decisions should
> have been deferred to a Haskell Prime committee mean, to me, that the
> hope is that they would have been rejected. That the Haskell Prime
> committee should have just vetoed these proposals that something like
> 80% or more of practicing Haskell users (as far as we can tell) wanted
> for years before they finally happened. That the Haskell Prime
> committee should be responsible for enforcing the very status quo that
> led to the CLC in the first place, where proposals with broad support
> but minority dissent never pass for various core modules.
>
> If this is the case, then one could simply repose the earlier
> question: why should most of these people stick around to obey by the
> Haskell Prime committee's pronouncements, instead of getting to work
> on a language that incorporates their input?
>
> And if it isn't, then I don't ultimately understand what the
> complaints are. We try to accomplish the (large) changes in a manner
> that allows transition via refactoring over multiple versions (and as
> I mentioned earlier, some complaints are that we compromised _too
> much_ for this). And in light of the more recent complaints, it's even
> been decided that our time frames should be longer. Rolling up changes
> into a report just seems like it makes transitions less smooth. Unless
> the idea is to make GHC capable of switching out entire base library
> sets; but someone has to implement that, and once you have it, it
> makes the report specifications _less_ essential.
>
> Anyhow, that's my history lesson. Take it as you (all) will.
>
> Cheers,
> -- Dan
>
> On Wed, Oct 21, 2015 at 10:43 AM, Geoffrey Mainland
> <[hidden email]> wrote:
>> On 10/21/2015 07:30 AM, Simon Peyton Jones wrote:
>>> Friends
>>>
>>> I think it's good for us to debate the question of how we should balance innovation against change; and how we should make those decisions in future.  Geoff's message had some good ideas, especially this bit:
>>>
>>> |  Proposal 2: After a suitable period of discussion on the libraries list, the
>>> |  Core Libraries Committee will summarize the arguments for and against a
>>> |  proposal and post it, along with a (justified) preliminary decision, to a
>>> |  low-traffic, announce-only email list. After another suitable period of
>>> |  discussion, they will issue a final decision. What is a suitable period of
>>> |  time? Perhaps that depends on the properties of the proposal, such as
>>> |  whether it breaks backwards compatibility.
>>>
>>> Identifying major changes to the libraries, and having a better publicised, more RFC-like process for deliberating them, would be a good thing.  I believe that the Core Libraries committee is thinking actively about this.
>>>
>>> |  Personally, I think AMP was the right thing to do, but I don't think FTP was
>>> |  the right thing.
>>>
>>> These make good examples to motivate future changes to our process.  But in the end FTP was subject to a pretty broad deliberative process, precisely along the lines that Geoff suggests above.  We had two clearly-articulated alternatives, a discrete call for opinions broadcast to every Haskell channel we could find, a decent interval for people to respond, and (as it turned out) a very clear preponderance of opinion in one direction.  In a big community, even a broad consultation may yield a result that some think is ill-advised.  That's part of the joyful burden of being a big community.
>>>
>>> Let's look forward, not back.  I think we can do better in future than we have done in the past.  I don't think we can hope for unanimity, but I think we can reasonably seek
>>>
>>>  * transparency;
>>>  * clarity about what decisions are on the table;
>>>  * broad consultation about decisions that affect
>>>     a broad constituency; and
>>>  * a decent opportunity to debate them without having
>>>     to be involved in massive email threads.  Let's try do to that.
>>>
>>> Simon
>>>
>>> PS: For what it's worth I'm less keen on Geoff's other proposal:
>>>
>>> |  Proposal 3: A decision regarding any proposal that significantly affects
>>> |  backwards compatibility is within the purview of the Haskell Prime
>>> |  Committee, not the Core Libraries Committee.
>>>
>>> *Precisely* the same issues will arise whether it's CLC or HPC.  And the HPC is going to be jolly busy with language issues. Moving the question from one group to another risks avoiding the issue rather than addressing it.
>> For the record, I am also not sure Proposal 3 is a good idea :)
>>
>> However, I do think we could clarify what the respective
>> responsibilities of the core libraries committee and Haskell Prime
>> committees are.
>>
>> One possible choice is that the core libraries committee is responsible
>> for changes to the core libraries that do not affect libraries in the
>> report. It is meant to be nimble, able to quickly deal with the large
>> volume of library changes that do not impact backwards compatibility.
>>
>> In this scenario, the Haskell Prime committee, using a longer
>> deliberative process, would consider the more impactful library changes
>> and batch them up into new reports.
>>
>> You are absolutely correct that moving the question to the Haskell Prime
>> committee risks pushing the issue around. The idea behind the separation
>> outlined above is to reduce the treadmill; the two bodies use different
>> processes, with different time frames, to arrive at decisions. Some
>> library decisions may deserve a longer deliberative process.
>>
>> Cheers,
>> Geoff
>> _______________________________________________
>> Libraries mailing list
>> [hidden email]
>> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

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Re: Breaking Changes and Long Term Support Haskell

Henrik Nilsson-2
In reply to this post by Dan Doel
Hi Dan,

Thanks for the history lesson. You do make many valid points.
And I also want to say thank you for the hard work that CLC
has put in.

Let me nevertheless react to a handful of things:

 > And the answer was that there should be some body empowered to decide
 > to move forward with these ideas, even if there is some dissent. And
 > frankly, it wasn't going to be the prime committee, because it hadn't
 > shown any activity in something like 3 years at the time, and even
 > when it was active, it didn't make anywhere near the sort of changes
 > that were being discussed.

I have seen criticism of the Haskell committee along similar lines
before, but I think it is overly simplistic, and arguably unfair,
for two reasons. First, squarely measuring accomplishment in terms
of number or scope of changes, which seems to be the gist (apologies
if I misunderstand), is, frankly, naive. In many ways, what didn't
change, for example, can be at least as important as what did for
establishing a language as a viable and attractive proposition for
large scale work. And the value of that for a language community as a
whole is hard to overstate. Now, I have no real data to back up that the
committee achieved that. But it is clear that Haskell has grown
a lot over the past 5 to 10 years, i.e. well before AMP, FTP, etc.
So maybe the last instance of the Haskell committee actually achieved
a great deal more than some seem willing to give it credit for.

Secondly, let us not forget that at least one highly controversial
and very breaking change was adopted for Haskell 2010: dropping
n + k patterns. The reason that went through was that there were very
compelling technical reasons and ultimately a clear case for
the advantages outweighing the disadvantages by a wide margin. So it is
not as if a committee cannot make controversial decisions. That does
presuppose that the majority of its members fundamentally have the
interest of the community at large at the fore, and are willing to take
good arguments aboard, rather than being prone to take stances mainly
for "political" reasons. Fortunately, I strongly believe the Haskell
community by and large is rational in this sense.

 > Forgive me if I'm wrong, but suggestions that these decisions should
 > have been deferred to a Haskell Prime committee mean, to me, that the
 > hope is that they would have been rejected.

OK, you are forgiven! I can of course only speak for myself, but I have
followed this discussion very carefully, and discussed with many people
in person. And as far as I can tell, there is absolutely nothing to
suggest that the reason that those who are unhappy with the process by
which AMP, FTP etc. happened (or by some of the details of those
proposals)  raise the possibility that the Haskell committee in one way
or another should have been (or in the future be) involved at least as
a vetting instance when it comes to the most far-reaching library
changes, is a secret hope of "death by committee".

Anyway, whether there are one or two committees ultimately does not
really matter, as long as both are widely seen to have a wide mandate
for whatever they are entrusted with, and as long as the process for
far-reaching changes is sufficiently robust and long.

 > That the Haskell Prime
 > committee should have just vetoed these proposals that something like
 > 80% or more of practicing Haskell users (as far as we can tell) wanted
 > for years before they finally happened.

Now, I have no desire to diminish the significance of the outcome of
that poll. Nor have I any desire to be branded as an "anti-democrat".
But if I am, so be it: I am bracing myself.

However, I have to point out that there is a lot more to
well-functioning democracies than simple majority votes. Look at any
developed democracy and there are lots of checks and balances in place
to safe-guard the interests of an as broad part of the population as
possible. In a federated state, just to give one example, there is
often a bicameral parliament where the states (broadly) have equal say
in one of the chambers irrespective of their size.

And yes, the workings of democracies are slow, sometimes painfully
so, but fundamentally that is for good reason.

To return to the case of a programming language community,
it is pretty much by definition going to be the case that a small
part of that community will be hit disproportionately hard by
changes to the language and/or its core libraries.

Their interests need to be adequately safeguarded too, or they will
surely jump ship in search of high and dry ground rather than run the
risk of drowning in the next wave of changes.

This, to the best of my understanding, is where I and others who
are suggesting that far-reaching changes should go past a
committee with a clear mandate and a sufficiently robust and long
process are coming from.

And I believe this is also what underlies Lennart's sentiment:

 > I think voting to decide these kind of issues a terrible idea; we
 > might as well throw dice.

Best,

/Henrik

--
Henrik Nilsson
School of Computer Science
The University of Nottingham
[hidden email]




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Re: Breaking Changes and Long Term Support Haskell

Tony Morris-4
In reply to this post by Simon Peyton Jones
Thanks Dan and others on CLC for your hard work and endurance.


On 22/10/15 07:48, Simon Peyton Jones wrote:

> While we are here, let me say
>
>   A BIG THANK YOU TO THE CORE LIBRARIES COMMITTEE
>
> Library design has a lot of detail, and a lot of competing priorities.  I am personally very grateful to the CLC for the work they put into this. Like many crucial tasks it's one that often seems to attract more complaints than thanks, but they are doing us all a huge service, and at significant cost in terms of their most precious and inelastic commodity: their personal time.
>
> Remember, as Dan says, before the CLC we no process whatsoever for library evolution... various people made various patches, and there was no way of getting anything substantial done.  So we are far far further on than before.
>
> Still not perfect, as my last post said. But still: THANK YOU.
>
> Simon
>
> | -----Original Message-----
> | From: Dan Doel [mailto:[hidden email]]
> | Sent: 21 October 2015 22:23
> | To: Geoffrey Mainland
> | Cc: Simon Peyton Jones; Augustsson, Lennart; Henrik Nilsson; haskell-
> | [hidden email] List; Haskell Libraries
> | Subject: Re: Breaking Changes and Long Term Support Haskell
> |
> | Hello,
> |
> | I'm Dan Doel. I'm on the core libraries committee (though I'm speaking
> | only for myself). As I recall, one of the reasons I got tapped for it
> | was due to my having some historical knowledge about Haskell; not
> | because I was there, but because I've gone back and looked at some old
> | reports and whatnot (and sometimes think they're better than what we
> | have now).
> |
> | But, I was around (of course) when the core libraries committee
> | started up, so perhaps I can play the role of historian for this as
> | well.
> |
> | The reason the committee exists is because a couple years ago, people
> | brought up the ideas that were finally realized in the
> | Applicative-Monad proposal and the Foldable-Traversable proposal. A
> | lot of people weighed in saying they thought they were a good idea,
> | and significantly fewer people weighed in saying they thought that it
> | shouldn't happen for various reasons---roughly the same things that
> | people are still bringing up about these proposals.
> |
> | This wasn't the first time that happened, either. I think it was
> | widely agreed among most users that Functor should be a superclass of
> | Monad since I started learning Haskell around 10 years ago. And once
> | Applicative was introduced, it was agreed that that should go in the
> | middle of the two. But it appeared that it would never happen, despite
> | a significant majority thinking it should, because no one wanted to do
> | anything without pretty much unanimous consent.
> |
> | So, one question that got raised is: why should this majority of
> | people even use Haskell/GHC anymore? Why shouldn't they start using
> | some other language that will let them change 15-year-old mistakes, or
> | adapt to ideas that weren't even available at that time (but are still
> | fairly old and established, all things considered). And the answer was
> | that there should be some body empowered to decide to move forward
> | with these ideas, even if there is some dissent. And frankly, it
> | wasn't going to be the prime committee, because it hadn't shown any
> | activity in something like 3 years at the time, and even when it was
> | active, it didn't make anywhere near the sort of changes that were
> | being discussed.
> |
> | And the kicker to me is, many things that people are complaining about
> | again (e.g. the FTP) were the very things that the committee was
> | established to execute. I don't think we had a formal vote on that
> | proposal, because we didn't need to. Our existence was in part to
> | execute that proposal (and AMP). And then a year ago, when it was
> | finally time to release the changes, there was another ruckus. And we
> | still didn't have a CLC vote on the matter. What we did was conduct a
> | community poll, and then SPJ reviewed the submissions. But I don't
> | mean to pass the buck to him, because I'm pretty sure he was worried
> | that we were crazy, and overstepping our bounds. Just, the results of
> | the survey were sufficient for him to not overrule us.
> |
> | So my point is this: there seems to be some sentiment that the core
> | libraries committee is unsound, and making bad decisions. But the
> | complaints are mostly not even about actual decisions we made (aside
> | from maybe Lennart Augustsson's, where he is unhappy with details of
> | the FTP that you can blame on us, but were designed to break the least
> | code, instead of being the most elegant; if we had pleased him more,
> | we would have pleased others less). They are about the reasons for
> | founding the committee in the first place. You can blame us, if you
> | like, because I think it's certain that we would have approved them if
> | we had formally voted. We just didn't even need to do so.
> |
> | Forgive me if I'm wrong, but suggestions that these decisions should
> | have been deferred to a Haskell Prime committee mean, to me, that the
> | hope is that they would have been rejected. That the Haskell Prime
> | committee should have just vetoed these proposals that something like
> | 80% or more of practicing Haskell users (as far as we can tell) wanted
> | for years before they finally happened. That the Haskell Prime
> | committee should be responsible for enforcing the very status quo that
> | led to the CLC in the first place, where proposals with broad support
> | but minority dissent never pass for various core modules.
> |
> | If this is the case, then one could simply repose the earlier
> | question: why should most of these people stick around to obey by the
> | Haskell Prime committee's pronouncements, instead of getting to work
> | on a language that incorporates their input?
> |
> | And if it isn't, then I don't ultimately understand what the
> | complaints are. We try to accomplish the (large) changes in a manner
> | that allows transition via refactoring over multiple versions (and as
> | I mentioned earlier, some complaints are that we compromised _too
> | much_ for this). And in light of the more recent complaints, it's even
> | been decided that our time frames should be longer. Rolling up changes
> | into a report just seems like it makes transitions less smooth. Unless
> | the idea is to make GHC capable of switching out entire base library
> | sets; but someone has to implement that, and once you have it, it
> | makes the report specifications _less_ essential.
> |
> | Anyhow, that's my history lesson. Take it as you (all) will.
> |
> | Cheers,
> | -- Dan
> |
> | On Wed, Oct 21, 2015 at 10:43 AM, Geoffrey Mainland
> | <[hidden email]> wrote:
> | > On 10/21/2015 07:30 AM, Simon Peyton Jones wrote:
> | >> Friends
> | >>
> | >> I think it's good for us to debate the question of how we should
> | balance innovation against change; and how we should make those decisions
> | in future.  Geoff's message had some good ideas, especially this bit:
> | >>
> | >> |  Proposal 2: After a suitable period of discussion on the libraries
> | list, the
> | >> |  Core Libraries Committee will summarize the arguments for and
> | against a
> | >> |  proposal and post it, along with a (justified) preliminary decision,
> | to a
> | >> |  low-traffic, announce-only email list. After another suitable period
> | of
> | >> |  discussion, they will issue a final decision. What is a suitable
> | period of
> | >> |  time? Perhaps that depends on the properties of the proposal, such
> | as
> | >> |  whether it breaks backwards compatibility.
> | >>
> | >> Identifying major changes to the libraries, and having a better
> | publicised, more RFC-like process for deliberating them, would be a good
> | thing.  I believe that the Core Libraries committee is thinking actively
> | about this.
> | >>
> | >> |  Personally, I think AMP was the right thing to do, but I don't think
> | FTP was
> | >> |  the right thing.
> | >>
> | >> These make good examples to motivate future changes to our process.
> | But in the end FTP was subject to a pretty broad deliberative process,
> | precisely along the lines that Geoff suggests above.  We had two clearly-
> | articulated alternatives, a discrete call for opinions broadcast to every
> | Haskell channel we could find, a decent interval for people to respond,
> | and (as it turned out) a very clear preponderance of opinion in one
> | direction.  In a big community, even a broad consultation may yield a
> | result that some think is ill-advised.  That's part of the joyful burden
> | of being a big community.
> | >>
> | >> Let's look forward, not back.  I think we can do better in future than
> | we have done in the past.  I don't think we can hope for unanimity, but I
> | think we can reasonably seek
> | >>
> | >>  * transparency;
> | >>  * clarity about what decisions are on the table;
> | >>  * broad consultation about decisions that affect
> | >>     a broad constituency; and
> | >>  * a decent opportunity to debate them without having
> | >>     to be involved in massive email threads.  Let's try do to that.
> | >>
> | >> Simon
> | >>
> | >> PS: For what it's worth I'm less keen on Geoff's other proposal:
> | >>
> | >> |  Proposal 3: A decision regarding any proposal that significantly
> | affects
> | >> |  backwards compatibility is within the purview of the Haskell Prime
> | >> |  Committee, not the Core Libraries Committee.
> | >>
> | >> *Precisely* the same issues will arise whether it's CLC or HPC.  And
> | the HPC is going to be jolly busy with language issues. Moving the
> | question from one group to another risks avoiding the issue rather than
> | addressing it.
> | >
> | > For the record, I am also not sure Proposal 3 is a good idea :)
> | >
> | > However, I do think we could clarify what the respective
> | > responsibilities of the core libraries committee and Haskell Prime
> | > committees are.
> | >
> | > One possible choice is that the core libraries committee is responsible
> | > for changes to the core libraries that do not affect libraries in the
> | > report. It is meant to be nimble, able to quickly deal with the large
> | > volume of library changes that do not impact backwards compatibility.
> | >
> | > In this scenario, the Haskell Prime committee, using a longer
> | > deliberative process, would consider the more impactful library changes
> | > and batch them up into new reports.
> | >
> | > You are absolutely correct that moving the question to the Haskell Prime
> | > committee risks pushing the issue around. The idea behind the separation
> | > outlined above is to reduce the treadmill; the two bodies use different
> | > processes, with different time frames, to arrive at decisions. Some
> | > library decisions may deserve a longer deliberative process.
> | >
> | > Cheers,
> | > Geoff
> | > _______________________________________________
> | > Libraries mailing list
> | > [hidden email]
> | >
> | https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fmail.haske
> | ll.org%2fcgi-
> | bin%2fmailman%2flistinfo%2flibraries&data=01%7c01%7csimonpj%40064d.mgd.mic
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> | 11db47%7c1&sdata=zL3zfXigvfpvdXL%2bhWuGoQzUUhGp%2bg8ofO1tGaFzlvE%3d
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Re: [Haskell-cafe] Monad of no `return` Proposal (MRP): Moving `return` out of `Monad`

John Wiegley-2
In reply to this post by Henrik Nilsson-2
>>>>> Henrik Nilsson <[hidden email]> writes:

> So before breaking anything more, that being code, research papers, books,
> what people have learned, or even the community itself, it is time to very
> carefully think about what the appropriate processes should be for going
> forward.

Hi Henrik,

I'd really like to understand your position better, since I'm pretty sure it's
not just a juxtaposition between "change" or "no change".

How would you like to see Haskell grow in the future? What does a successful
process to evolve the language look like to you? Is it the change causing you
difficulty, or the way we arrive at the change?

John
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Re: Breaking Changes and Long Term Support Haskell

Dan Doel
In reply to this post by Geoffrey Mainland
For proposal 3, I don't see what difference it makes whether a
refreshed Haskell committee or a new libraries committee makes
decisions that affect backwards compatibility. A name doesn't ensure
good decision making. The only difference I can see is that the
Haskell committee might only publish final decisions every couple
years. But the Haskell report also isn't designed to describe
migration plans between feature revisions; unless the plan is to start
incorporating library deprecation and whatnot into the report (which
would be odd to me). But that would just be doing the same thing
slower, so it'd be little different than making library changes over 6
to 9 GHC versions instead of 3.

For proposal 2, I don't know how effective it will be in practice. I
believe it is already the job of a proposal submitter to summarize the
arguments made about it, according to the library proposal guidelines.
We could post those summaries to another list. But unless more people
promise they will be diligent about reading that list, I'm not sure
that one factor in these dust ups (surprise) will actually be any
different.

Also, if amount of discussion is at issue, I'm not sure I agree. For
AMP, I was waiting a decade, more or less. I thought we should do it,
other people thought we shouldn't because it would break things. I
don't know what more there was to discuss, except there was more stuff
to break the longer we waited.

As for FTP, some aspects only became known as the proposal was
implemented, and I don't know that they would have been realized
regardless of how long the proposal were discussed. And then we still
had a month or so of discussion after the implementation was
finalized, on the cusp of GHC 7.10 being released. So how much more
_was_ needed, that people are now discussing it again?

If it's just about documenting more things, there's certainly no harm in that.

For 1, I don't have a very strong opinion. If pressed, I would
probably express some similar sentiments to Henrik. I certainly don't
think Haskell would be nearly as good as it is if it were a simple
majority vote by all users (and I probably wouldn't use it if that's
how things were decided). Would a community vote for libraries
committee be better than appointment by people who previously held the
power (but have more to do than any human can accomplish)? I don't
know.

I should say, though, that things are not now run by simple majority
vote. What we conducted a year ago was a survey, where people
submitted their thoughts. I didn't get to read them, because they were
private, and it wasn't my decision to make. But it was not just +80
-20.

With regard to your last paragraph, unless I've missed something (and
I confess that I haven't read every comment in these threads), the
recent resignations didn't express disagreement with the decision
making process. They expressed disagreement with the (technical)
decisions (and their effects). I don't see how a different process
could have solved that unless it is expected that it would have made
different decisions.

-- Dan

On Wed, Oct 21, 2015 at 6:18 PM, Geoffrey Mainland <[hidden email]> wrote:

> Hi Dan,
>
> Thank you for the historical perspective.
>
> I was careful not to criticize the committee. Instead, I made three
> concrete proposals with the hope that they would help orient a conversation.
>
> It sounds like you are not for proposal 3. How about the other two?
>
> My original email stated my underlying concern: we are losing valuable
> members of the community not because of the technical decisions that are
> being made, but because of the process by which they are being made.
> That concern is what drove my proposals. It is perfectly valid to think
> that that loss was the inevitable price of progress, but that is not my
> view.
>
> Cheers,
> Geoff
>
> On 10/21/15 5:22 PM, Dan Doel wrote:
>> Hello,
>>
>> I'm Dan Doel. I'm on the core libraries committee (though I'm speaking
>> only for myself). As I recall, one of the reasons I got tapped for it
>> was due to my having some historical knowledge about Haskell; not
>> because I was there, but because I've gone back and looked at some old
>> reports and whatnot (and sometimes think they're better than what we
>> have now).
>>
>> But, I was around (of course) when the core libraries committee
>> started up, so perhaps I can play the role of historian for this as
>> well.
>>
>> The reason the committee exists is because a couple years ago, people
>> brought up the ideas that were finally realized in the
>> Applicative-Monad proposal and the Foldable-Traversable proposal. A
>> lot of people weighed in saying they thought they were a good idea,
>> and significantly fewer people weighed in saying they thought that it
>> shouldn't happen for various reasons---roughly the same things that
>> people are still bringing up about these proposals.
>>
>> This wasn't the first time that happened, either. I think it was
>> widely agreed among most users that Functor should be a superclass of
>> Monad since I started learning Haskell around 10 years ago. And once
>> Applicative was introduced, it was agreed that that should go in the
>> middle of the two. But it appeared that it would never happen, despite
>> a significant majority thinking it should, because no one wanted to do
>> anything without pretty much unanimous consent.
>>
>> So, one question that got raised is: why should this majority of
>> people even use Haskell/GHC anymore? Why shouldn't they start using
>> some other language that will let them change 15-year-old mistakes, or
>> adapt to ideas that weren't even available at that time (but are still
>> fairly old and established, all things considered). And the answer was
>> that there should be some body empowered to decide to move forward
>> with these ideas, even if there is some dissent. And frankly, it
>> wasn't going to be the prime committee, because it hadn't shown any
>> activity in something like 3 years at the time, and even when it was
>> active, it didn't make anywhere near the sort of changes that were
>> being discussed.
>>
>> And the kicker to me is, many things that people are complaining about
>> again (e.g. the FTP) were the very things that the committee was
>> established to execute. I don't think we had a formal vote on that
>> proposal, because we didn't need to. Our existence was in part to
>> execute that proposal (and AMP). And then a year ago, when it was
>> finally time to release the changes, there was another ruckus. And we
>> still didn't have a CLC vote on the matter. What we did was conduct a
>> community poll, and then SPJ reviewed the submissions. But I don't
>> mean to pass the buck to him, because I'm pretty sure he was worried
>> that we were crazy, and overstepping our bounds. Just, the results of
>> the survey were sufficient for him to not overrule us.
>>
>> So my point is this: there seems to be some sentiment that the core
>> libraries committee is unsound, and making bad decisions. But the
>> complaints are mostly not even about actual decisions we made (aside
>> from maybe Lennart Augustsson's, where he is unhappy with details of
>> the FTP that you can blame on us, but were designed to break the least
>> code, instead of being the most elegant; if we had pleased him more,
>> we would have pleased others less). They are about the reasons for
>> founding the committee in the first place. You can blame us, if you
>> like, because I think it's certain that we would have approved them if
>> we had formally voted. We just didn't even need to do so.
>>
>> Forgive me if I'm wrong, but suggestions that these decisions should
>> have been deferred to a Haskell Prime committee mean, to me, that the
>> hope is that they would have been rejected. That the Haskell Prime
>> committee should have just vetoed these proposals that something like
>> 80% or more of practicing Haskell users (as far as we can tell) wanted
>> for years before they finally happened. That the Haskell Prime
>> committee should be responsible for enforcing the very status quo that
>> led to the CLC in the first place, where proposals with broad support
>> but minority dissent never pass for various core modules.
>>
>> If this is the case, then one could simply repose the earlier
>> question: why should most of these people stick around to obey by the
>> Haskell Prime committee's pronouncements, instead of getting to work
>> on a language that incorporates their input?
>>
>> And if it isn't, then I don't ultimately understand what the
>> complaints are. We try to accomplish the (large) changes in a manner
>> that allows transition via refactoring over multiple versions (and as
>> I mentioned earlier, some complaints are that we compromised _too
>> much_ for this). And in light of the more recent complaints, it's even
>> been decided that our time frames should be longer. Rolling up changes
>> into a report just seems like it makes transitions less smooth. Unless
>> the idea is to make GHC capable of switching out entire base library
>> sets; but someone has to implement that, and once you have it, it
>> makes the report specifications _less_ essential.
>>
>> Anyhow, that's my history lesson. Take it as you (all) will.
>>
>> Cheers,
>> -- Dan
>>
>> On Wed, Oct 21, 2015 at 10:43 AM, Geoffrey Mainland
>> <[hidden email]> wrote:
>>> On 10/21/2015 07:30 AM, Simon Peyton Jones wrote:
>>>> Friends
>>>>
>>>> I think it's good for us to debate the question of how we should balance innovation against change; and how we should make those decisions in future.  Geoff's message had some good ideas, especially this bit:
>>>>
>>>> |  Proposal 2: After a suitable period of discussion on the libraries list, the
>>>> |  Core Libraries Committee will summarize the arguments for and against a
>>>> |  proposal and post it, along with a (justified) preliminary decision, to a
>>>> |  low-traffic, announce-only email list. After another suitable period of
>>>> |  discussion, they will issue a final decision. What is a suitable period of
>>>> |  time? Perhaps that depends on the properties of the proposal, such as
>>>> |  whether it breaks backwards compatibility.
>>>>
>>>> Identifying major changes to the libraries, and having a better publicised, more RFC-like process for deliberating them, would be a good thing.  I believe that the Core Libraries committee is thinking actively about this.
>>>>
>>>> |  Personally, I think AMP was the right thing to do, but I don't think FTP was
>>>> |  the right thing.
>>>>
>>>> These make good examples to motivate future changes to our process.  But in the end FTP was subject to a pretty broad deliberative process, precisely along the lines that Geoff suggests above.  We had two clearly-articulated alternatives, a discrete call for opinions broadcast to every Haskell channel we could find, a decent interval for people to respond, and (as it turned out) a very clear preponderance of opinion in one direction.  In a big community, even a broad consultation may yield a result that some think is ill-advised.  That's part of the joyful burden of being a big community.
>>>>
>>>> Let's look forward, not back.  I think we can do better in future than we have done in the past.  I don't think we can hope for unanimity, but I think we can reasonably seek
>>>>
>>>>  * transparency;
>>>>  * clarity about what decisions are on the table;
>>>>  * broad consultation about decisions that affect
>>>>     a broad constituency; and
>>>>  * a decent opportunity to debate them without having
>>>>     to be involved in massive email threads.  Let's try do to that.
>>>>
>>>> Simon
>>>>
>>>> PS: For what it's worth I'm less keen on Geoff's other proposal:
>>>>
>>>> |  Proposal 3: A decision regarding any proposal that significantly affects
>>>> |  backwards compatibility is within the purview of the Haskell Prime
>>>> |  Committee, not the Core Libraries Committee.
>>>>
>>>> *Precisely* the same issues will arise whether it's CLC or HPC.  And the HPC is going to be jolly busy with language issues. Moving the question from one group to another risks avoiding the issue rather than addressing it.
>>> For the record, I am also not sure Proposal 3 is a good idea :)
>>>
>>> However, I do think we could clarify what the respective
>>> responsibilities of the core libraries committee and Haskell Prime
>>> committees are.
>>>
>>> One possible choice is that the core libraries committee is responsible
>>> for changes to the core libraries that do not affect libraries in the
>>> report. It is meant to be nimble, able to quickly deal with the large
>>> volume of library changes that do not impact backwards compatibility.
>>>
>>> In this scenario, the Haskell Prime committee, using a longer
>>> deliberative process, would consider the more impactful library changes
>>> and batch them up into new reports.
>>>
>>> You are absolutely correct that moving the question to the Haskell Prime
>>> committee risks pushing the issue around. The idea behind the separation
>>> outlined above is to reduce the treadmill; the two bodies use different
>>> processes, with different time frames, to arrive at decisions. Some
>>> library decisions may deserve a longer deliberative process.
>>>
>>> Cheers,
>>> Geoff
>>> _______________________________________________
>>> Libraries mailing list
>>> [hidden email]
>>> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>
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Re: Breaking Changes and Long Term Support Haskell

Taru Karttunen
In reply to this post by Geoffrey Mainland
On 21.10 17:42, Gregory Collins wrote:
> All I'm saying is that if we want to appeal to or cater to working software
> engineers, we have to be a lot less cavalier about causing more work for
> them, and we need to prize stability of the core infrastructure more
> highly. That'd be a broader cultural change, and that goes beyond process:
> it's policy.

I think that how the changes are handled can make a large difference.

E.g. if

A) Most of Hackage (including dependencies) compiles with new GHC.
(stack & stackage helps somewhat)

B) There is an automated tool that can be used to fix most code
to compile with new versions of GHC without warnings or CPP.

C) Hackage displays vocally what works with which versions of
GHC (Status reports do help somewhat)

Then I think much of the complaints would go away.

- Taru Karttunen
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Re: Breaking Changes and Long Term Support Haskell

Edward Kmett-2
On Thu, Oct 22, 2015 at 2:04 AM, Taru Karttunen <[hidden email]> wrote:
E.g. if

A) Most of Hackage (including dependencies) compiles with new GHC.
(stack & stackage helps somewhat)

B) There is an automated tool that can be used to fix most code
to compile with new versions of GHC without warnings or CPP.

C) Hackage displays vocally what works with which versions of
GHC (Status reports do help somewhat)
 
Then I think much of the complaints would go away.
 
If we had those things, indeed they would!

However, beyond A (GHC 7.10 was tested more extensively against hackage/stackage than any previous release of Haskell by far!), the others require various degrees of engineering effort, including some way to deal with refactoring code that already has CPP in it, more extensive build-bot services, etc. and those sort of non-trivial artifacts just haven't been forthcoming. =/

I would be very happy if those things showed up, however.

-Edward

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Re: Breaking Changes and Long Term Support Haskell

Edward Kmett-2
In reply to this post by Geoffrey Mainland
On Wed, Oct 21, 2015 at 8:42 PM, Gregory Collins <[hidden email]> wrote:

On Wed, Oct 21, 2015 at 3:18 PM, Geoffrey Mainland <[hidden email]> wrote:
My original email stated my underlying concern: we are losing valuable
members of the community not because of the technical decisions that are
being made, but because of the process by which they are being made.
[If] you're doing research you're on the treadmill, almost by definition, and you're delighted that we're finally making some rapid progress on fixing up some of the longstanding warts.

If you're a practitioner, you are interested in using Haskell for, y'know, writing programs. You're probably in one of two camps: you're in "green field" mode writing a lot of new code (early stage startups, prototype work, etc), or you're maintaining/extending programs you've already written that are out "in the field" for you doing useful work. Laura Wingerd calls this the "annealing temperature" of software, and I think this is a nice metaphor to describe it. How tolerant you are of ecosystem churn depends on what your temperature is: and I think it should be obvious to everyone that Haskell having "success" for programming work would mean that lots of useful and correct programs get written, so everyone who is in the former camp will cool over time to join the latter.

I've made the point before and I don't really want to belabor it: our de facto collective posture towards breaking stuff, especially in the past few years, has been extremely permissive, and this alienates people who are maintaining working programs.

Even among people who purported to be teaching Haskell or using Haskell today in industry the margin of preference for the concrete FTP proposal was ~79%. This was considerably higher than I expected in two senses. One: there were a lot more people who claimed to be in one of those two roles than I expected by far, and two: their appetite for change was higher than I expected. I initially expected to see a stronger "academic vs. industry" split in the poll, but the groups were only distinguishable by a few percentage point delta, so while I expected roughly the end percentage of the poll, based on the year prior I'd spent running around the planet to user group meetings and the like, I expected it mostly because I expected more hobbyists and less support among industrialists.

I'm actually firmly of the belief that the existing committee doesn't really have process issues, and in fact, that often it's been pretty careful to minimize the impact of the changes it wants to make. As others have pointed out, lots of the churn actually comes from platform libraries, which are out of the purview of this group.

Historically we've had a bit of a split personality on this front. Nothing that touches the Prelude had changed in 17 years. On the other hand the platform libraries had maintained a pretty heavy rolling wave of breakage the entire time I've been around in the community. On a more experimental feature front, I've lost count of the number of different things we've done to Typeable or template-haskell.
 
All I'm saying is that if we want to appeal to or cater to working software engineers, we have to be a lot less cavalier about causing more work for them, and we need to prize stability of the core infrastructure more highly. That'd be a broader cultural change, and that goes beyond process: it's policy.

The way things are shaping up, we've had 17 years of rock solid stability, 1 release that incorporated changes that were designed to minimize impact, to the point that the majority of the objections against them are of the form where people would prefer that we broke _more_ code, to get a more sensible state. Going forward, it looks like the next 2 GHC releases will have basically nothing affecting the Prelude, and there will be another punctuation in the equilibrium around 8.4 as the next set of changes kicks in over 8.4 and 8.6 That gives 2 years worth of advance notice of pending changes, and a pretty strong guarantee from the committee that you should be able to maintain code with a 3 release window without running afoul of warnings or needing CPP.

So, out of curiosity, what additional stability policy is it that you seek?

-Edward

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Re: Breaking Changes and Long Term Support Haskell

Herbert Valerio Riedel
In reply to this post by Taru Karttunen
On 2015-10-22 at 08:04:10 +0200, Taru Karttunen wrote:

[...]

> B) There is an automated tool that can be used to fix most code
> to compile with new versions of GHC without warnings or CPP.

Fyi, Alan is currently working on levaraging HaRe[1] in

 https://github.com/alanz/Hs2010To201x (the `parsing-only` branch)

and it's already showing great promise. However, tools like this will
only be able to handle the no-brainer cases, as in general it's a NP
hard problem. But luckily, those boring mechanical refactorings usually
represent the vast majority, and that's the tedious work we want
tooling to assist us most with.


> C) Hackage displays vocally what works with which versions of
> GHC (Status reports do help somewhat)


I.e. something like

  http://matrix.hackage.haskell.org/package/text

? :-)


 [1]: Btw, here's a recent talk which also mentions the use-case of using
      HaRe to update between Haskell Report revisions or `base` versions:
 
      https://skillsmatter.com/skillscasts/6539-a-new-foundation-for-refactoring-ghc-exactprint
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Re: Breaking Changes and Long Term Support Haskell

Taru Karttunen
On 22.10 09:04, Herbert Valerio Riedel wrote:
> Fyi, Alan is currently working on levaraging HaRe[1] in
>
>  https://github.com/alanz/Hs2010To201x (the `parsing-only` branch)
>
> and it's already showing great promise. However, tools like this will
> only be able to handle the no-brainer cases, as in general it's a NP
> hard problem. But luckily, those boring mechanical refactorings usually
> represent the vast majority, and that's the tedious work we want
> tooling to assist us most with.

Yes, getting it 99% there as an automated tool would be enough
for most cases.


> > C) Hackage displays vocally what works with which versions of
> > GHC (Status reports do help somewhat)
>
>
> I.e. something like
>
>   http://matrix.hackage.haskell.org/package/text

Yes! Is there a reason that it is not displayed on
http://hackage.haskell.org/package/text which only
displays a link to Status of a 7.8.3 build?

How many percent of Hackage is built with matrix.h.h.o
and is there a plan to integrate it into Hackage pages?

- Taru Karttunen
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Re: Breaking Changes and Long Term Support Haskell

Geoffrey Mainland
In reply to this post by Edward Kmett-2
On 10/22/2015 02:40 AM, Edward Kmett wrote:

> On Wed, Oct 21, 2015 at 8:42 PM, Gregory Collins
> <[hidden email] <mailto:[hidden email]>> wrote:
>
>
>     On Wed, Oct 21, 2015 at 3:18 PM, Geoffrey Mainland
>     <[hidden email] <mailto:[hidden email]>> wrote:
>
>         My original email stated my underlying concern: we are losing
>         valuable
>         members of the community not because of the technical
>         decisions that are
>         being made, but because of the process by which they are being
>         made.
>
>     [If] you're doing research you're on the treadmill, almost by
>     definition, and you're delighted that we're finally making some
>     rapid progress on fixing up some of the longstanding warts.
>
>     If you're a practitioner, you are interested in using Haskell for,
>     y'know, writing programs. You're probably in one of two camps:
>     you're in "green field" mode writing a lot of new code (early
>     stage startups, prototype work, etc), or you're
>     maintaining/extending programs you've already written that are out
>     "in the field" for you doing useful work. Laura Wingerd calls this
>     the "annealing temperature" of software, and I think this is a
>     nice metaphor to describe it. How tolerant you are of ecosystem
>     churn depends on what your temperature is: and I think it should
>     be obvious to everyone that Haskell having "success" for
>     programming work would mean that lots of useful and correct
>     programs get written, so everyone who is in the former camp will
>     cool over time to join the latter.
>
>
>     I've made the point before and I don't really want to belabor it:
>     our de facto collective posture towards breaking stuff, especially
>     in the past few years, has been extremely permissive, and this
>     alienates people who are maintaining working programs.
>
>
> Even among people who purported to be teaching Haskell or using
> Haskell today in industry the margin of preference for the concrete
> FTP proposal was ~79%. This was considerably higher than I expected in
> two senses. One: there were a lot more people who claimed to be in one
> of those two roles than I expected by far, and two: their appetite for
> change was higher than I expected. I initially expected to see a
> stronger "academic vs. industry" split in the poll, but the groups
> were only distinguishable by a few percentage point delta, so while I
> expected roughly the end percentage of the poll, based on the year
> prior I'd spent running around the planet to user group meetings and
> the like, I expected it mostly because I expected more hobbyists and
> less support among industrialists.
>
>     I'm actually firmly of the belief that the existing committee
>     doesn't really have process issues, and in fact, that often it's
>     been pretty careful to minimize the impact of the changes it wants
>     to make. As others have pointed out, lots of the churn actually
>     comes from platform libraries, which are out of the purview of
>     this group.
>
>
> Historically we've had a bit of a split personality on this front.
> Nothing that touches the Prelude had changed in 17 years. On the other
> hand the platform libraries had maintained a pretty heavy rolling wave
> of breakage the entire time I've been around in the community. On a
> more experimental feature front, I've lost count of the number of
> different things we've done to Typeable or template-haskell.
>  
>
>     All I'm saying is that if we want to appeal to or cater to working
>     software engineers, we have to be a lot less cavalier about
>     causing more work for them, and we need to prize stability of the
>     core infrastructure more highly. That'd be a broader cultural
>     change, and that goes beyond process: it's policy.
>
>
> The way things are shaping up, we've had 17 years of rock solid
> stability, 1 release that incorporated changes that were designed to
> minimize impact, to the point that the majority of the objections
> against them are of the form where people would prefer that we broke
> _more_ code, to get a more sensible state. Going forward, it looks
> like the next 2 GHC releases will have basically nothing affecting the
> Prelude, and there will be another punctuation in the equilibrium
> around 8.4 as the next set of changes kicks in over 8.4 and 8.6 That
> gives 2 years worth of advance notice of pending changes, and a pretty
> strong guarantee from the committee that you should be able to
> maintain code with a 3 release window without running afoul of
> warnings or needing CPP.
>
> So, out of curiosity, what additional stability policy is it that you
> seek?

Thanks to you and Dan [1], I now have a greater understanding and
appreciation for where the committee has been coming from. My new
understanding is that the changes that were formalized in AMP, FTP, and
MRP were the basis for the committee's creation. It also seems that
there are more changes in the pipeline that have not yet been made into
proposals, e.g., pulling (>>) out of Control.Monad [2]. Part of
"stability" is signaling change as far ahead as possible. The committee
has put a lot of effort into this, which I appreciate! However, as each
of these proposal has come down the pipeline, I never realized that they
were part of a larger master plan.

1) What is the master plan, and where is it documented, even if this
document is not up to the standard of a proposal? What is the final
target, and when might we expect it to be reached? What is in the
pipeline after MRP?

Relatedly, guidance on how to write code now so that it will be
compatible with future changes helps mitigate the stability issue.

2) How can I write code that makes use of the Prelude so that it will
work with every new GHC release over the next 3 years? 5 years? For
example, how can I write a Monad instance now, knowing the changes that
are coming, so that the instance will work with every new GHC release
for the next 3 years? 5 years? If the answer is "you can't," then when
might I be able to do such a thing? As of 8.4? 8.6? I'm embarrassed to
say I don't know the answer!

Finally, if none of these changes broke Prelude backwards compatibility,
far fewer people would be complaining :) Of course, we can't always make
progress without breaking things, but a more deliberative process might
offer an opportunity to make progress while still preserving backwards
compatibility. Take AMP for example. There were at least two [3] [4]
proposals for preserving backwards compatibility. Investigating them
would have taken time and delayed AMP, yes, but why the rush?

3) Can we have a process that allows more deliberation over, and wider
publicity for, changes that break backwards compatibility? The goal of
such a process would not be to prevent change, but to allow more time to
find possible solution to the issue of backwards compatibility.

My proposal for a low-traffic mailing list where all proposals were
announced was meant to provide wider publicity.

Personally, I think these proposals do indeed fix a lot of warts in the
language. As a researcher who uses actively uses Haskell every day,
these warts have had approximately zero impact on me for the past
(almost) decade, and I would be perfectly content if they were never
fixed. The only pain I can recall enduring is having to occasionally
write an orphan Applicative instance. I have been importing Prelude
hiding mapM for years. I have been importing Control.Applicative for
years. Neither has been painful. Dealing with AMP? I'm working on a
collaborative research project that is stuck on 7.8 because of AMP. I
agree, that seems silly, but whether or not it is silly, it is an impact
I feel.

One way to look at these proposals is to ask the question "Wouldn't the
language be nicer if all these changes were made?" Another is to ask the
question "Does the fact that these changes have not been made make your
life as a Haskell programmer more difficult in any significant way?" I
answer "yes" to the former and "no" to the latter. Is our stance that
answering "yes" to the former question is enough to motivate braking
change? Shouldn't a answer "no" to the latter question cause some
hesitation?

Maybe there are a lot of people who answer "yes" to both questions. I
would like to know! But does having return in the Monad class really
cause anyone anything other than existential pain?

Cheers,
Geoff

[1] https://mail.haskell.org/pipermail/libraries/2015-October/026390.html
[2] https://mail.haskell.org/pipermail/libraries/2015-September/026158.html
[3] https://ghc.haskell.org/trac/ghc/wiki/InstanceTemplates
[4] https://ghc.haskell.org/trac/ghc/wiki/IntrinsicSuperclasses

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Re: Breaking Changes and Long Term Support Haskell

Geoffrey Mainland
On 10/22/2015 11:02 AM, Matthias Hörmann wrote:
> I would say that the need to import Control.Applicative in virtually
> every module manually
> definitely caused some pain before AMP.

In this particular case, there is a trade off between breaking code on
the one hand and having to write some import statements on the other. I
find writing some extra imports less painful than breaking (other
people's and my) code, but the other position is defensible as well. I
sense that I am in the minority, at least on the libraries list.

> I would also argue that a
> non-negligible amount
> of effort goes into teaching the warts, the reasons for the warts and
> how to work around them.

Which wart(s) in particular? All of them? Does having return (and (>>))
in Monad make teaching more difficult?

I teach Haskell beginners, and I found that AMP made explaining monads
slightly more difficult because it served as a source of confusion for
my students.

On the other hand, the warts provide a teachable moment once students
understand all this stuff :)

>> Dealing with AMP? I'm working on a collaborative research project that is stuck on 7.8 because of AMP.
> I am curious what exactly about AMP causes your research project to be
> "stuck" on GHC 7.8
> considering we have had multiple people mention how little effort it
> took to update even large codebases.
> I think it would be useful information to have to plan future changes
> in a way that might avoid
> your issues.

I was hoping that mentioning this wouldn't distract from the three main
(numbered) questions I posed below. Alas.

If I were working alone, AMP wouldn't be a huge deal. I could fix the
code for 7.10 compatibility, but then unless everyone switches to 7.10,
changes to the codebase made by someone using 7.8, e.g., defining a new
Monad instance, could break things on 7.10 again. It's easier to stick
with 7.8. Any time spent dealing with compatibility issues is time not
spent writing actual code.

I outlined one possible path to avoid this kind of issue: spend more
time thinking about ways to maintain compatibility. We had proposals for
doing this with AMP.

Cheers,
Geoff

>
> On Thu, Oct 22, 2015 at 3:29 PM, Geoffrey Mainland <[hidden email]> wrote:
>> On 10/22/2015 02:40 AM, Edward Kmett wrote:
>>> On Wed, Oct 21, 2015 at 8:42 PM, Gregory Collins
>>> <[hidden email] <mailto:[hidden email]>> wrote:
>>>
>>>
>>>     On Wed, Oct 21, 2015 at 3:18 PM, Geoffrey Mainland
>>>     <[hidden email] <mailto:[hidden email]>> wrote:
>>>
>>>         My original email stated my underlying concern: we are losing
>>>         valuable
>>>         members of the community not because of the technical
>>>         decisions that are
>>>         being made, but because of the process by which they are being
>>>         made.
>>>
>>>     [If] you're doing research you're on the treadmill, almost by
>>>     definition, and you're delighted that we're finally making some
>>>     rapid progress on fixing up some of the longstanding warts.
>>>
>>>     If you're a practitioner, you are interested in using Haskell for,
>>>     y'know, writing programs. You're probably in one of two camps:
>>>     you're in "green field" mode writing a lot of new code (early
>>>     stage startups, prototype work, etc), or you're
>>>     maintaining/extending programs you've already written that are out
>>>     "in the field" for you doing useful work. Laura Wingerd calls this
>>>     the "annealing temperature" of software, and I think this is a
>>>     nice metaphor to describe it. How tolerant you are of ecosystem
>>>     churn depends on what your temperature is: and I think it should
>>>     be obvious to everyone that Haskell having "success" for
>>>     programming work would mean that lots of useful and correct
>>>     programs get written, so everyone who is in the former camp will
>>>     cool over time to join the latter.
>>>
>>>
>>>     I've made the point before and I don't really want to belabor it:
>>>     our de facto collective posture towards breaking stuff, especially
>>>     in the past few years, has been extremely permissive, and this
>>>     alienates people who are maintaining working programs.
>>>
>>>
>>> Even among people who purported to be teaching Haskell or using
>>> Haskell today in industry the margin of preference for the concrete
>>> FTP proposal was ~79%. This was considerably higher than I expected in
>>> two senses. One: there were a lot more people who claimed to be in one
>>> of those two roles than I expected by far, and two: their appetite for
>>> change was higher than I expected. I initially expected to see a
>>> stronger "academic vs. industry" split in the poll, but the groups
>>> were only distinguishable by a few percentage point delta, so while I
>>> expected roughly the end percentage of the poll, based on the year
>>> prior I'd spent running around the planet to user group meetings and
>>> the like, I expected it mostly because I expected more hobbyists and
>>> less support among industrialists.
>>>
>>>     I'm actually firmly of the belief that the existing committee
>>>     doesn't really have process issues, and in fact, that often it's
>>>     been pretty careful to minimize the impact of the changes it wants
>>>     to make. As others have pointed out, lots of the churn actually
>>>     comes from platform libraries, which are out of the purview of
>>>     this group.
>>>
>>>
>>> Historically we've had a bit of a split personality on this front.
>>> Nothing that touches the Prelude had changed in 17 years. On the other
>>> hand the platform libraries had maintained a pretty heavy rolling wave
>>> of breakage the entire time I've been around in the community. On a
>>> more experimental feature front, I've lost count of the number of
>>> different things we've done to Typeable or template-haskell.
>>>
>>>
>>>     All I'm saying is that if we want to appeal to or cater to working
>>>     software engineers, we have to be a lot less cavalier about
>>>     causing more work for them, and we need to prize stability of the
>>>     core infrastructure more highly. That'd be a broader cultural
>>>     change, and that goes beyond process: it's policy.
>>>
>>>
>>> The way things are shaping up, we've had 17 years of rock solid
>>> stability, 1 release that incorporated changes that were designed to
>>> minimize impact, to the point that the majority of the objections
>>> against them are of the form where people would prefer that we broke
>>> _more_ code, to get a more sensible state. Going forward, it looks
>>> like the next 2 GHC releases will have basically nothing affecting the
>>> Prelude, and there will be another punctuation in the equilibrium
>>> around 8.4 as the next set of changes kicks in over 8.4 and 8.6 That
>>> gives 2 years worth of advance notice of pending changes, and a pretty
>>> strong guarantee from the committee that you should be able to
>>> maintain code with a 3 release window without running afoul of
>>> warnings or needing CPP.
>>>
>>> So, out of curiosity, what additional stability policy is it that you
>>> seek?
>> Thanks to you and Dan [1], I now have a greater understanding and
>> appreciation for where the committee has been coming from. My new
>> understanding is that the changes that were formalized in AMP, FTP, and
>> MRP were the basis for the committee's creation. It also seems that
>> there are more changes in the pipeline that have not yet been made into
>> proposals, e.g., pulling (>>) out of Control.Monad [2]. Part of
>> "stability" is signaling change as far ahead as possible. The committee
>> has put a lot of effort into this, which I appreciate! However, as each
>> of these proposal has come down the pipeline, I never realized that they
>> were part of a larger master plan.
>>
>> 1) What is the master plan, and where is it documented, even if this
>> document is not up to the standard of a proposal? What is the final
>> target, and when might we expect it to be reached? What is in the
>> pipeline after MRP?
>>
>> Relatedly, guidance on how to write code now so that it will be
>> compatible with future changes helps mitigate the stability issue.
>>
>> 2) How can I write code that makes use of the Prelude so that it will
>> work with every new GHC release over the next 3 years? 5 years? For
>> example, how can I write a Monad instance now, knowing the changes that
>> are coming, so that the instance will work with every new GHC release
>> for the next 3 years? 5 years? If the answer is "you can't," then when
>> might I be able to do such a thing? As of 8.4? 8.6? I'm embarrassed to
>> say I don't know the answer!
>>
>> Finally, if none of these changes broke Prelude backwards compatibility,
>> far fewer people would be complaining :) Of course, we can't always make
>> progress without breaking things, but a more deliberative process might
>> offer an opportunity to make progress while still preserving backwards
>> compatibility. Take AMP for example. There were at least two [3] [4]
>> proposals for preserving backwards compatibility. Investigating them
>> would have taken time and delayed AMP, yes, but why the rush?
>>
>> 3) Can we have a process that allows more deliberation over, and wider
>> publicity for, changes that break backwards compatibility? The goal of
>> such a process would not be to prevent change, but to allow more time to
>> find possible solution to the issue of backwards compatibility.
>>
>> My proposal for a low-traffic mailing list where all proposals were
>> announced was meant to provide wider publicity.
>>
>> Personally, I think these proposals do indeed fix a lot of warts in the
>> language. As a researcher who uses actively uses Haskell every day,
>> these warts have had approximately zero impact on me for the past
>> (almost) decade, and I would be perfectly content if they were never
>> fixed. The only pain I can recall enduring is having to occasionally
>> write an orphan Applicative instance. I have been importing Prelude
>> hiding mapM for years. I have been importing Control.Applicative for
>> years. Neither has been painful. Dealing with AMP? I'm working on a
>> collaborative research project that is stuck on 7.8 because of AMP. I
>> agree, that seems silly, but whether or not it is silly, it is an impact
>> I feel.
>>
>> One way to look at these proposals is to ask the question "Wouldn't the
>> language be nicer if all these changes were made?" Another is to ask the
>> question "Does the fact that these changes have not been made make your
>> life as a Haskell programmer more difficult in any significant way?" I
>> answer "yes" to the former and "no" to the latter. Is our stance that
>> answering "yes" to the former question is enough to motivate braking
>> change? Shouldn't a answer "no" to the latter question cause some
>> hesitation?
>>
>> Maybe there are a lot of people who answer "yes" to both questions. I
>> would like to know! But does having return in the Monad class really
>> cause anyone anything other than existential pain?
>>
>> Cheers,
>> Geoff
>>
>> [1] https://mail.haskell.org/pipermail/libraries/2015-October/026390.html
>> [2] https://mail.haskell.org/pipermail/libraries/2015-September/026158.html
>> [3] https://ghc.haskell.org/trac/ghc/wiki/InstanceTemplates
>> [4] https://ghc.haskell.org/trac/ghc/wiki/IntrinsicSuperclasses

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Re: Breaking Changes and Long Term Support Haskell

Mario Blažević
In reply to this post by Geoffrey Mainland
On 15-10-22 09:29 AM, Geoffrey Mainland wrote:
> ...
>
> 1) What is the master plan, and where is it documented, even if this
> document is not up to the standard of a proposal? What is the final
> target, and when might we expect it to be reached? What is in the
> pipeline after MRP?
>
> Relatedly, guidance on how to write code now so that it will be
> compatible with future changes helps mitigate the stability issue.

        I have been fully in favour of all the proposals implemented so far,
and I think that having an explicit master plan would be a great idea.
It would address some of the process-related objections that have been
raised, and it would provide a fixed long-term target that would be much
easier to make the whole community aware of and contribute to.

        For that purpose, the master plan should be advertised directly on the
front page of haskell.org. Once we have it settled and agreed, the
purpose of the base-library commitee would essentially become to figure
out the details like the timeline and code migration path. One thing
they wouldn't need to worry about is whether anybody disagrees with
their goals.


> 2) How can I write code that makes use of the Prelude so that it will
> work with every new GHC release over the next 3 years? 5 years? For
> example, how can I write a Monad instance now, knowing the changes that
> are coming, so that the instance will work with every new GHC release
> for the next 3 years? 5 years? If the answer is "you can't," then when
> might I be able to do such a thing? As of 8.4? 8.6? I'm embarrassed to
> say I don't know the answer!

        From the discussions so far it appears that the answer for 3 years (or
at least the next 3 GHC releases) would be to write the code that works
with the current GHC and base, but this policy has not been codified
anywhere yet. Knowing the upcoming changes doesn't help with making your
code any more robust, and I think that's a shame. We could have a
two-pronged policy:

- code that works and compiles with the latest GHC with no *warnings*
will continue to work and compile with no *errors* with the following 2
releases, and
- code that also follows the forward-compatibility recommendations
current for that version of GHC will continue to work and compile with
no *errors* with the following 4 releases.

        The forward-compatibility recommendations would become a part of the
online GHC documentation so nobody complains they didn't know about
them. Personally, I'd prefer if the recommendations were built into the
compiler itself as a new class of warnings, but then (a) some people
would insist on turning them on together with -Werror and then complain
when their builds break and (b) this would increase the pressure on GHC
implementors.


> Finally, if none of these changes broke Prelude backwards compatibility,
> far fewer people would be complaining :) Of course, we can't always make
> progress without breaking things, but a more deliberative process might
> offer an opportunity to make progress while still preserving backwards
> compatibility. Take AMP for example. There were at least two [3] [4]
> proposals for preserving backwards compatibility. Investigating them
> would have taken time and delayed AMP, yes, but why the rush?

        Because they have been investigated for years with no effect.


> 3) Can we have a process that allows more deliberation over, and wider
> publicity for, changes that break backwards compatibility? The goal of
> such a process would not be to prevent change, but to allow more time to
> find possible solution to the issue of backwards compatibility.

        I doubt we can, but this question has already been answered by others.

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