In all honesty, Typing Haskell in Haskell is about as far as anyone should push typechecking and type inference while claiming to still work in a functional style. I don't think a good GADT pre-spec looks like functional programming at all, it's a [constraint] logic programming problem and part of what we're looking to establish is the minimum information flow people can expect during inference for a given amount of syntactic effort. I'm not saying I never write the implementations in haskell! But they tend to involve a lot of "how to implement the constraint system" and then a bunch of transliterated typing rules. A good spec for "enough annotation this should work easily" would be useful as something that permits other implementations to experiment with different extensions in combination though! On 22/04/2016 18:55, José Manuel Calderón Trilla wrote:

Hi Richard,

...

As a concrete suggestion, I wonder if we should have two goals:

1. Write down an updated standard for Haskell.

2. Write down pre-standards for several extensions. I agree with both of these. It may even be useful to use goal 2 as a stepping stone to determine what extensions should receive the extra attention necessary (if any) to be part of goal 1. Were you thinking that these pre-standards would look something like Mark Jones's 'Typing Haskell in Haskell' paper? A simplified and clear specification in the form of a Haskell program would go a long way in clarifying the meaning of certain extensions. To use your example, you could imagine an implementation of GADTs that forms the baseline of what the GADT extension should mean (implementations should accept at least what this one does). That might be too ambitious though.

A lot of the 'obvious' extensions were discussed that last time the Haskell Prime committee was active, so a lot of groundwork has been laid already. The most important step right now is empowering people to move forward with the process.

Herbert Valerio Riedel is the chair of the reboot, and as such gets final say on who is a member of the committee and any timeline for deciding. That being said, I think the aim should be to have the committee membership decided soon and start discussing what the priorities should be. I'm partial to suggesting a face to face meeting at ICFP, but realize that it is difficult for many to attend to ICFP.

Cheers,

José

On Fri, Apr 22, 2016 at 9:33 AM, Richard Eisenberg wrote:

...

I stand by ready to debate standards and would enjoy moving this process forward. However, I'm not in a position where I can lead at the moment -- just too consumed by other tasks right now.

As a concrete suggestion, I wonder if we should have two goals:

1. Write down an updated standard for Haskell.

2. Write down pre-standards for several extensions.

About (2): I'm very sympathetic to a recent post on Haskell-cafe about having formal descriptions of language extensions. It is not our purview to document GHC. However, several extensions are in very common use, but might not be quite ready for a language standard. Chief among these, in my opinion, is GADTs. GADTs are problematic from a standardization standpoint because it's quite hard to specify when a GADT pattern-match type-checks, without resorting to discussion of unification variables. For this reason, I would be hesitant about putting GADTs in a standard. On the other hand, it shouldn't be too hard to specify some sort of minimum implementation that individual compilers can build on. I'm calling such a description a "pre-standard".

Thoughts?

Richard

On Apr 21, 2016, at 5:22 PM, José Manuel Calderón Trilla wrote:

...

Hello all,

I'm curious if there is any progress on the reboot of the Haskell Prime committee. It has been six months since the closing of nominations and there hasn't been any word that I'm aware of. I've also spoken to a few others that have self-nominated and they too have not heard any news.

Personally, I feel that a new standard is very important for the future health of the community. Several threads on the mailing list and posts on the web, such as one on reddit today [1], show a desire from the community for a major consolidation effort.

If there is any way that I can help the process along I would be glad to do so. It would be a shame to allow for the enthusiasm for a new committee fade away.

Cheers,

José

[1]: https://www.reddit.com/r/haskell/comments/4fsuvu/can_we_have_xhaskell2016_wh... _______________________________________________ Haskell-prime mailing list Haskell-prime@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-prime

---

Haskell-prime mailing list Haskell-prime@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-prime

Agreed - the appropriate means for specifying the type system is something I'm not sure we have a truly good answer for at this point alas. We're way past being able to rely on an informal "H-M + constraints from typeclasses" style description if we want to describe even extensions that have been around 15+ years. (I am not on the committee etc etc, just have spent much time pondering related issues!) On 22/04/2016 20:49, Andres Loeh wrote:

Hi.

I've been talking to Herbert from time to time, and I know he's having a draft announcement lying around, and is still planning on properly starting the process soon, and has (this is my opinion, not his) just been falling into the trap of waiting for a "good moment" which then never comes.

I'm personally still eager to get the discussions about a new standard started.

While it's true that the old Haskell Prime committee has been doing good work in creating some sort of catalogue of issues and extensions at the time, it's still far from proper standardization. And indeed, I think the bulk of the work that goes into a new standard in my opinon is to work out all the corner cases and the actual specification of the extensions. It's less important which ones ultimately go in or stay out, but actually specfiying them properly is already going to be a good step forward.

Cheers, Andres

On Fri, Apr 22, 2016 at 7:55 PM, José Manuel Calderón Trilla wrote:

...

Hi Richard,

...

As a concrete suggestion, I wonder if we should have two goals:

1. Write down an updated standard for Haskell.

2. Write down pre-standards for several extensions. I agree with both of these. It may even be useful to use goal 2 as a stepping stone to determine what extensions should receive the extra attention necessary (if any) to be part of goal 1. Were you thinking that these pre-standards would look something like Mark Jones's 'Typing Haskell in Haskell' paper? A simplified and clear specification in the form of a Haskell program would go a long way in clarifying the meaning of certain extensions. To use your example, you could imagine an implementation of GADTs that forms the baseline of what the GADT extension should mean (implementations should accept at least what this one does). That might be too ambitious though.

A lot of the 'obvious' extensions were discussed that last time the Haskell Prime committee was active, so a lot of groundwork has been laid already. The most important step right now is empowering people to move forward with the process.

Herbert Valerio Riedel is the chair of the reboot, and as such gets final say on who is a member of the committee and any timeline for deciding. That being said, I think the aim should be to have the committee membership decided soon and start discussing what the priorities should be. I'm partial to suggesting a face to face meeting at ICFP, but realize that it is difficult for many to attend to ICFP.

Cheers,

José

On Fri, Apr 22, 2016 at 9:33 AM, Richard Eisenberg wrote:

...

I stand by ready to debate standards and would enjoy moving this process forward. However, I'm not in a position where I can lead at the moment -- just too consumed by other tasks right now.

As a concrete suggestion, I wonder if we should have two goals:

1. Write down an updated standard for Haskell.

2. Write down pre-standards for several extensions.

About (2): I'm very sympathetic to a recent post on Haskell-cafe about having formal descriptions of language extensions. It is not our purview to document GHC. However, several extensions are in very common use, but might not be quite ready for a language standard. Chief among these, in my opinion, is GADTs. GADTs are problematic from a standardization standpoint because it's quite hard to specify when a GADT pattern-match type-checks, without resorting to discussion of unification variables. For this reason, I would be hesitant about putting GADTs in a standard. On the other hand, it shouldn't be too hard to specify some sort of minimum implementation that individual compilers can build on. I'm calling such a description a "pre-standard".

Thoughts?

Richard

On Apr 21, 2016, at 5:22 PM, José Manuel Calderón Trilla wrote:

...

Hello all,

I'm curious if there is any progress on the reboot of the Haskell Prime committee. It has been six months since the closing of nominations and there hasn't been any word that I'm aware of. I've also spoken to a few others that have self-nominated and they too have not heard any news.

Personally, I feel that a new standard is very important for the future health of the community. Several threads on the mailing list and posts on the web, such as one on reddit today [1], show a desire from the community for a major consolidation effort.

If there is any way that I can help the process along I would be glad to do so. It would be a shame to allow for the enthusiasm for a new committee fade away.

Cheers,

José

[1]: https://www.reddit.com/r/haskell/comments/4fsuvu/can_we_have_xhaskell2016_wh... _______________________________________________ Haskell-prime mailing list Haskell-prime@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-prime

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