haskell-src-exts maintenance

Matthew Pickering

29 Jun 2015 29 Jun '15

8:13 a.m.

Dear List, There are a large number of untriaged pull requests and issues currently open on the issue tracker for haskell-src-exts. The tool is widely used by tool writers but the last commit to the project is now over 6 months ago. I think it is important to get this work merged and update the parser to support modern language features introduced in GHC 7.8 and 7.10. I would personally be capable of helping with this effort but before doing so I would appreciate a comment from the current maintainers as to the current status of the project. So, 1. Does anyone know if Niklas or Peter plan to return to the project? 2. Is there anyone else who is interested in updating the HSE parser? Matt

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Christian Marie

1 Jul 1 Jul

2:54 a.m.

On Mon, Jun 29, 2015 at 01:13:54PM +0100, Matthew Pickering wrote:

...

There are a large number of untriaged pull requests and issues currently open on the issue tracker for haskell-src-exts. The tool is widely used by tool writers but the last commit to the project is now over 6 months ago.

I was about to post this exact message after searching around for a good hour.

...

1. Does anyone know if Niklas or Peter plan to return to the project?

I didn't contact them directly. I'm not so sure if Nicklas is active at all.

...

2. Is there anyone else who is interested in updating the HSE parser?

Yes, I've got at least one fix I'd like to make myself and I'd be happy to do some triaging and releasing too. Most of the PRs look pretty good. Roman Cheplyaka is a maintainer on hackage, hopefully he sees and knows something aobut this. I'll email some people in the haskell suite group directly if this thread doesn't go anywhere.

Mike Izbicki

3:18 a.m.

I've always been curious why we need a stand alone package for parsing haskell code? Last time I tried to use haskell-src-exts (admittedly several years ago), it was out of date and didn't support the extensions I wanted. It seems like the ideal solution would be to have GHC's parsing code exposed as a library. And this library would be compatible with template haskell. Is there some technical reason why this is inherently difficult? Or is it just an accident of history that things didn't develop that way? On Tue, Jun 30, 2015 at 11:54 PM, Christian Marie wrote:

...

On Mon, Jun 29, 2015 at 01:13:54PM +0100, Matthew Pickering wrote:

...
There are a large number of untriaged pull requests and issues currently open on the issue tracker for haskell-src-exts. The tool is widely used by tool writers but the last commit to the project is now over 6 months ago.

I was about to post this exact message after searching around for a good hour.

...
1. Does anyone know if Niklas or Peter plan to return to the project?

I didn't contact them directly. I'm not so sure if Nicklas is active at all.

...
2. Is there anyone else who is interested in updating the HSE parser?

Yes, I've got at least one fix I'd like to make myself and I'd be happy to do some triaging and releasing too. Most of the PRs look pretty good.

Roman Cheplyaka is a maintainer on hackage, hopefully he sees and knows something aobut this.

I'll email some people in the haskell suite group directly if this thread doesn't go anywhere.

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

Alan & Kim Zimmerman

3:33 a.m.

I think the main argument against using GHC is that the library is intimately tied to the current compiler, so writing a tool to process haskell source which is compiler version independent it tricky, requiring lots of CPP. I am starting to wonder if it does not make sense to make a companion library for each GHC release with is just the parser/AST, and so can be used with any other compiler, even a non-ghc one. Alan On Wed, Jul 1, 2015 at 9:18 AM, Mike Izbicki wrote:

...

I've always been curious why we need a stand alone package for parsing haskell code? Last time I tried to use haskell-src-exts (admittedly several years ago), it was out of date and didn't support the extensions I wanted.

It seems like the ideal solution would be to have GHC's parsing code exposed as a library. And this library would be compatible with template haskell. Is there some technical reason why this is inherently difficult? Or is it just an accident of history that things didn't develop that way?

On Tue, Jun 30, 2015 at 11:54 PM, Christian Marie wrote:

...
On Mon, Jun 29, 2015 at 01:13:54PM +0100, Matthew Pickering wrote:

...
There are a large number of untriaged pull requests and issues currently open on the issue tracker for haskell-src-exts. The tool is widely used by tool writers but the last commit to the project is now over 6 months ago.

I was about to post this exact message after searching around for a good hour.

...
1. Does anyone know if Niklas or Peter plan to return to the project?

I didn't contact them directly. I'm not so sure if Nicklas is active at all.

...
2. Is there anyone else who is interested in updating the HSE parser?

Yes, I've got at least one fix I'd like to make myself and I'd be happy to do some triaging and releasing too. Most of the PRs look pretty good.

Roman Cheplyaka is a maintainer on hackage, hopefully he sees and knows something aobut this.

I'll email some people in the haskell suite group directly if this thread doesn't go anywhere.

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

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

Christian Marie

4:31 a.m.

On Wed, Jul 01, 2015 at 09:33:26AM +0200, Alan & Kim Zimmerman wrote:

...

I am starting to wonder if it does not make sense to make a companion library for each GHC release with is just the parser/AST, and so can be used with any other compiler, even a non-ghc one.

This would have been my intuition, I suspect it isn't that simple though. The duplication of effort does seem odd, and this would solve the problem of linters and the like always playing catch up. This is affecting many users. I, personally, have avoided extensions in the past when haskell-src-exts threw its toys out of the cot (specifically LambdaCase, then DataKinds).

Matthew Pickering

27 Jul 27 Jul

5:13 a.m.

Hi Peter, Do you know when you have some time to go through the recently submitted patches? If it's not soon then please could you add myself and Christian to the maintainers so that we can perform some short term maintenance. My immediate plan of action would be 1. Immediately cut a 1.17 release from the master branch as it contains much better parsing of lifted constructors which are becoming more prevalent. 2. Review and merge recent pull requests. 3. Update the parser as far as possible with missing features. 4. Release 1.18 with these improvements within 1 month. Matt On Wed, Jul 1, 2015 at 10:31 AM, Christian Marie wrote:

...

On Wed, Jul 01, 2015 at 09:33:26AM +0200, Alan & Kim Zimmerman wrote:

...
I am starting to wonder if it does not make sense to make a companion library for each GHC release with is just the parser/AST, and so can be used with any other compiler, even a non-ghc one.

This would have been my intuition, I suspect it isn't that simple though.

The duplication of effort does seem odd, and this would solve the problem of linters and the like always playing catch up.

This is affecting many users. I, personally, have avoided extensions in the past when haskell-src-exts threw its toys out of the cot (specifically LambdaCase, then DataKinds).

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

Neil Mitchell

28 Jul 28 Jul

11:49 a.m.

As a very heavy HSE user (HLint and Hoogle), who has had a reasonably close working relationship with all of Niklas (my SoC mentor and my SoC mentee), Roman and Peter (a fellow supercompiler developer) and Matt (currently hacking on HLint), I thought I should weigh in. The current state of HSE is a little forlorn - there are 22 open pull requests, everything from reducing algorithm complexity (an accidental n^3), fixing the default encoding (should be UTF8) and lots of actual parser fixes. A lot of this is good stuff, and the high level of external contributions is a really good sign. But they need to be merged and reviewed, and it seems the bandwidth just isn't there at the moment. Given Matt's comments on the existing tickets, and the triage he's already performing on the repo, I have high hopes that Matt could provide a bit more of the time and attention. Peter, perhaps a co-maintainer would be good for a little while?

...

If it's not soon then please could you add myself and Christian to the maintainers so that we can perform some short term maintenance. My immediate plan of action would be

1. Immediately cut a 1.17 release from the master branch as it contains much better parsing of lifted constructors which are becoming more prevalent. 2. Review and merge recent pull requests. 3. Update the parser as far as possible with missing features. 4. Release 1.18 with these improvements within 1 month.

Awesome! Although as a preference I'd go for as much of 2 as you can in a couple of days before doing 1 - a lot of the patches are simple and valuable, and a 2 day wait isn't going to be too problematic. Thanks, Neil

Matthew Pickering

1 Jul 1 Jul

5:29 a.m.

Separating the parser from GHC is not trivial. Firstly the parser takes DynFlags as an argument which is used in all stages of the GHC pipeline to keep track of which flags are enabled. Second - this would also require all syntactic datatypes to be extracted into a separate module as well as all the various datatypes which they depend on as well, for example RdrName depends on Name which is only introduced after the parsing stage but would also need to be extracted. HSE is also desirable because it already has momentum, a not insignificant number of programs use tooling based on HSE. Secondly, it is much easier to manipulate in general than the GHC AST, especially the difference between the annotated and unannotated source. All this being said, I would much prefer a world where GHC was easier to use as a library for this kind of thing as it is difficult to remain consistent between the two but keeping HSE updated should remain important in the near future. Matt On Wed, Jul 1, 2015 at 8:18 AM, Mike Izbicki wrote:

...

I've always been curious why we need a stand alone package for parsing haskell code? Last time I tried to use haskell-src-exts (admittedly several years ago), it was out of date and didn't support the extensions I wanted.

It seems like the ideal solution would be to have GHC's parsing code exposed as a library. And this library would be compatible with template haskell. Is there some technical reason why this is inherently difficult? Or is it just an accident of history that things didn't develop that way?

On Tue, Jun 30, 2015 at 11:54 PM, Christian Marie wrote:

...
On Mon, Jun 29, 2015 at 01:13:54PM +0100, Matthew Pickering wrote:

...
There are a large number of untriaged pull requests and issues currently open on the issue tracker for haskell-src-exts. The tool is widely used by tool writers but the last commit to the project is now over 6 months ago.

I was about to post this exact message after searching around for a good hour.

...
1. Does anyone know if Niklas or Peter plan to return to the project?

I didn't contact them directly. I'm not so sure if Nicklas is active at all.

...
2. Is there anyone else who is interested in updating the HSE parser?

Yes, I've got at least one fix I'd like to make myself and I'd be happy to do some triaging and releasing too. Most of the PRs look pretty good.

Roman Cheplyaka is a maintainer on hackage, hopefully he sees and knows something aobut this.

I'll email some people in the haskell suite group directly if this thread doesn't go anywhere.

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

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

Roman Cheplyaka

3:31 a.m.

On 01/07/15 09:54, Christian Marie wrote:

...

On Mon, Jun 29, 2015 at 01:13:54PM +0100, Matthew Pickering wrote:

...
There are a large number of untriaged pull requests and issues currently open on the issue tracker for haskell-src-exts. The tool is widely used by tool writers but the last commit to the project is now over 6 months ago.

I was about to post this exact message after searching around for a good hour.

...
1. Does anyone know if Niklas or Peter plan to return to the project?

I didn't contact them directly. I'm not so sure if Nicklas is active at all.

...
2. Is there anyone else who is interested in updating the HSE parser?

Yes, I've got at least one fix I'd like to make myself and I'd be happy to do some triaging and releasing too. Most of the PRs look pretty good.

Roman Cheplyaka is a maintainer on hackage, hopefully he sees and knows something aobut this.

I'll email some people in the haskell suite group directly if this thread doesn't go anywhere.

I no longer maintain haskell-src-exts[1]. That said, I am happy to give maintainer rights on github and hackage to a new volunteer(s) unless Niklas or Peter (cc'd) objects. Just let me know your github and hackage usernames. [1]: https://ro-che.info/articles/2014-11-01-rebalancing-open-source-portfolio Roman

Erik Hesselink

3:50 a.m.

On Wed, Jul 1, 2015 at 9:31 AM, Roman Cheplyaka wrote:

...

On 01/07/15 09:54, Christian Marie wrote:

...
On Mon, Jun 29, 2015 at 01:13:54PM +0100, Matthew Pickering wrote:

...
There are a large number of untriaged pull requests and issues currently open on the issue tracker for haskell-src-exts. The tool is widely used by tool writers but the last commit to the project is now over 6 months ago.

I was about to post this exact message after searching around for a good hour.

...
1. Does anyone know if Niklas or Peter plan to return to the project?

I didn't contact them directly. I'm not so sure if Nicklas is active at all.

...
2. Is there anyone else who is interested in updating the HSE parser?

Yes, I've got at least one fix I'd like to make myself and I'd be happy to do some triaging and releasing too. Most of the PRs look pretty good.

Roman Cheplyaka is a maintainer on hackage, hopefully he sees and knows something aobut this.

I'll email some people in the haskell suite group directly if this thread doesn't go anywhere.

I no longer maintain haskell-src-exts[1]. That said, I am happy to give maintainer rights on github and hackage to a new volunteer(s) unless Niklas or Peter (cc'd) objects. Just let me know your github and hackage usernames.

I also have commit rights on github, and although I don't have enough free time to be official maintainer, I could merge the occasional pull request when I have some free time. I have not done so since I'm not the maintainer and I was added to the haskell-suite project for other packages, but if people would like me to be slightly more involved in haskell-src-exts, I could do that. Regards, Erik

Christian Marie

4:19 a.m.

On Wed, Jul 01, 2015 at 10:31:08AM +0300, Roman Cheplyaka wrote:

...

I no longer maintain haskell-src-exts[1]. That said, I am happy to give maintainer rights on github and hackage to a new volunteer(s) unless Niklas or Peter (cc'd) objects. Just let me know your github and hackage usernames.

[1]: https://ro-che.info/articles/2014-11-01-rebalancing-open-source-portfolio

Your link helped with context, thanks. If Niklas or Peter does not object: My hackage username: ChristianMarie http://hackage.haskell.org/user/ChristianMarie Github username: christian-marie https://github.com/christian-marie/

Roman Cheplyaka

4:27 a.m.

On 01/07/15 11:19, Christian Marie wrote:

...

On Wed, Jul 01, 2015 at 10:31:08AM +0300, Roman Cheplyaka wrote:

...
I no longer maintain haskell-src-exts[1]. That said, I am happy to give maintainer rights on github and hackage to a new volunteer(s) unless Niklas or Peter (cc'd) objects. Just let me know your github and hackage usernames.

[1]: https://ro-che.info/articles/2014-11-01-rebalancing-open-source-portfolio

Your link helped with context, thanks.

If Niklas or Peter does not object:

My hackage username: ChristianMarie http://hackage.haskell.org/user/ChristianMarie Github username: christian-marie https://github.com/christian-marie/

Since Peter has responded and remains an active maintainer, I'll leave it up to him.

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11 comments

7 participants

participants (7)

Alan & Kim Zimmerman
Christian Marie
Erik Hesselink
Matthew Pickering
Mike Izbicki
Neil Mitchell
Roman Cheplyaka