Posts by author thoughtpolice

GHC Weekly News - 2015/10/16

Hi *,

Welcome for the latest entry in the GHC Weekly News, which has been somewhat irregularly scheduled - but we're as busy as ever!

8.0.1 release roadmap

We're still steaming ahead on GHC 8.0.1 - any interested participants are suggested to look at the wiki:Status/GHC-8.0.1 page, to see where we're currently at.

These past few weeks have been good: we've gotten the first part of the overloaded record fields work in, and we have plans to land the kind equalities work in November. Furthermore, Simon Marlow, Peter Wortmann and Ben are working on reviewing all of the DWARF improvements, and hopefully the start of this work will land next week.

But 8.0 isn't the only thing that'll be getting released...

And some other minor releases

In a total, unprecedented upset - we're aiming to do three GHC releases in a fairly short amount of time.


Ben Gamari has been working on steadily hacking away at GHC 7.10.3, and the hopes are that we'll be able to ship it soon. This will fix several dozen bugs, some of which are critical for our users.

You can keep up to date by following the wiki:Status/GHC-7.10.3 page.


Simultaneously, your author will also be working on a GHC 7.8.5 release. While we were alerted a few months ago to this breakage, it seems rather unfortunate for the 7.8 series to remain broken on such a popular OS.

Furthermore, the "Three GHC Release Policy" for many authors - to support the last three major versions of GHC - would mean that 7.8 would be broken for OS X developers for an entire year until GHC 8.2.1. Which is a pretty unfortunate circumstance.

It's not expected the 7.8.5 release will contain any other fixes, however.

List chatter

(Over the past two weeks)

Noteworthy commits

(Over the past two weeks)

Closed tickets

(Over the past two weeks)

#10392, #7883, #10475, #10745, #10926, #9238, #10700, #10810, #10342, #365(!), #10361, #10929, #10563, #9907, #10513, #10868, #10932, #8920, #10516, #10416, #5966, #8335, #10520, #10687, #10571, #9058, #10939, #10938, #9590, #10949, #10153, #10947, #10948, #10936, #1883, #5289, #10733, #10950, #10611, #10959, #10960, #10831, #10796, #10890, #8010, #10216, #10965, #10953, #10964, #10931, #10714, #10888, #10633, #8652, #3971, #10882, #10977, #10267, and #10911.

GHC Weekly News - 2015/09/17

Hi *,

Welcome for the latest entry in the GHC Weekly News. It's been a little while, but here we are!

And your author has finally returned from his 8 week sabbatical, too! So without any futher ado, lets get going...

8.0.1 release roadmap

So HEAD has been steaming along pretty smoothly for the past few months now. After talking with Simon last week, we decided that the best course of action would be to release 8.0.1 (a super-major release) sometime around late February, which were the plans for 7.10 (modulo a few weeks due to the FTP debates). The current schedule is roughly:

  • November: Fork the new ghc-8.0 STABLE branch
    • At this point, master development will probably slow as we fix bugs.
    • This gives us 2 months or so until branch, from Today.
    • This is nice as the branch is close to the first RC.
  • December: First release candidate
  • Mid/late February: Final release.

"Why call it 8.0.1?", you ask? Because we have a lot of excellent features planned! I'm particularly partial to Richard's work for merging types and kinds (Phab:D808). But there's a lot of other stuff.

For all the nitty gritty details, be sure to check 8.0.1 status page to keep track of everything - it will be our prime source of information and coordination. And be sure to read my email to `ghc-devs` for more info.

... and a 7.10.3 release perhaps?

On top of this, we've been wondering if another release in the 7.10 branch should be done. Ben did the release shortly after I left, and for the most part looked pretty great. But there have been some snags, as usual.

So we're asking: who needs GHC 7.10.3? We'd really like to know of any major showstoppers you've found with 7.10 that are preventing you from using it. Especially if you're stuck or there's no clear workaround.

Currently, we're still not 100% committed to this course of action (since the release will take time away from other things). However, we'll keep the polls open for a while - so please get in touch with us if you need it! (Be sure to read my email for specific information.)

List chatter

(Over the past two weeks)

Noteworthy commits

(Over the past several weeks)

Closed tickets

(Over the past two weeks)

#10834, #10830, #10047, #9943, #1851, #1477, #8229, #8926, #8614, #10777, #8596, #10788, #9500, #9087, #10157, #10866, #10806, #10836, #10849, #10869, #10682, #10863, #10880, #10883, #10787, #8552, #10884, #7305, #5757, #9389, #8689, #10105, #8168, #9925, #10305, #4438, #9710, #10889, #10885, #10825, #10821, #10790, #10781, #9855, #9912, #10033, #9782, #10035, #9976, #10847, and #10865.

GHC Weekly News - 2015/06/10

Hi *,

Welcome for the latest entry in the GHC Weekly News. The past week, GHC HQ met up for a quick catch up on 7.10.2 (which you'll want to read up on, see below), and some other technical nonsense about some work we've been doing. As a result the current weekly notes have been slow - the current priority is the next release though, which leads us to...

7.10.2 status

7.10.2 is going to be out soon - our current plan is to have a release candidate on the weekend of Saturday the 13th, and the final release the next week. That means if you want something fixed, you'd better hollar very soon, or we're just not going to get to it!

If you're wondering what's currently been fixed/scheduled, the status page shows the current set of tickets we've fixed and plan on fixing.

List chatter

  • Jan Stolarek asks: in some cases, GHC will generate default instances or values, but that source code has no textual information location (for example, consider an instance clause without the where) - what do people think about fixing this, and are there anythings to look out for?
  • David Luposchainsky has opened a new thread - about moving fail out of Monad and into its own typeclass, MonadFail. This change is a request that's very long in the tooth (older than the AMP or FTP changes by a landslide), but David's proposal has a clearly set out goal to tackle compatibility, warnings, and implementation.

Noteworthy commits

Closed tickets

#10460, #7672, #9252, #9506, #10294, #5316, #10408, #10386, #9960, #10145, #9259, #10386, #9507, #8723, #10442, #5014, #4215, #10443, #8244, #10499, #10500, #10428, #10488, #10489, #10406, #10501, #10441, #10406, #10502, #9101, #9663, and #9945.

GHC Weekly News - 2015/06/03

Hi *,

It's that time once again - to get some info on what's happening in the world of GHC! It's been a quiet few weeks as a UK Holiday punted one of GHC HQ's meetings off, and this week we were only partially there.

The main point of discussion was 7.10.2, and continuing work on compiler performance. The good news is, the past few weeks have seen good work on both these fronts!

7.10.2 status

7.10.2 is swimming along very nicely - the status page shows the current set of tickets we've fixed and plan on fixing.

Not much has changed from last time, except we've fixed even more bugs! We're currently sitting at about 85 bugs fixed, some of them pretty important - code generation bugs, compiler performance fixes, some RTS and event manager work. Your author is actually quite happy with what GHC 7.10.2 looks like, at this rate.

List chatter

  • Facundo Dominguez asks: sometimes we want to create a static pointer in a function with a local definition, how can we do that? The current problem is the desugarer gets in the way and current approaches are currently rejected, but Facundo has some ideas/questions about a fix.

Noteworthy commits

Closed tickets

#10407, #10408, #10177, #10359, #10403, #10248, #9579, #10415, #10419, #10427, #10429, #10397, #10422, #10335, #10366, #10110, #10397, #10349, #10244, #8555, #8799, #9131, #10396, #10354, #10278, #9899, #3533, #9950, #10092, #9950, #10430, #9682, #9584, #10446, #10410, #10298, #10449, #10399, #7695, #10261, #8292, #10360, #10126, #10317, #10101, #10322, #10313, #10471, #10473, #7170, #10473, #10423, #10466, #8695, #10461, #10052, #10370, #10425, #10452, #10474,

GHC Weekly News - 2015/05/11

Hi *,

It's been a few weeks since the last news bulletin - this is the result of mostly quietness on behalf of the list and developers, and some sickness on behalf of your editor for several days there. But now there's actually some things to write here!

The past few weeks, GHC HQ has been having some quiet meetings mostly about bugfixes for a 7.10.2 release - as well as noodling about compiler performance. Austin has begun compiling his preliminary notes on the wiki, under the CompilerPerformance page, where we'll be trying to keep track of the ongoing performance story. Hopefully, GHC 7.12.1 will boast a bit better performance numbers.

There are a lot of users who are interested in this particular pain point, so please file tickets and CC yourself on bugs (like #10370), or feel free to help out!

7.10.2 status

There's been a bit of chatter about the lists about something on many peoples mind: the release of GHC 7.10.2. Most prominently, Mark Lentczner popped in to ask when the next GHC release will happen - in particular, he'd like to make a Haskell Platform release in lockstep with it (see below for a link to Mark's email).

Until recently, the actual desire for 7.10.2 wasn't totally clear, and at this point, GHC HQ hasn't firmly committed to the 7.10.2 release date. But if milestone:7.10.2 is any indicator, we've already closed over three dozen bugs, several of them high priority - and they keep coming in. So it seems likely people will want these fixes in their hands relatively soon.

Just remember: if you need a fix for 7.10.2, or have a bug you need us to look at, please email the ghc-devs list, file a ticket, and get our attention! Just be sure to set the milestone to 7.10.2.

List chatter

  • Niklas Hambüchen announced that he's backported the recent lightweight stack-trace support in GHC HEAD to GHC 7.10 and GHC 7.8 - meaning that users of these stable release can have informative call stack traces, even without profiling! FP Complete was interested in this feature, so they'd probably love to hear user input.
  • David Terei has written up a proposal on reconciling the existence of Roles with Safe Haskell, which caused us a lot of problems during the 7.8 release cycle. In particular, concerning the ability to break module abstractions and requiring programmers to safeguard abstractions through careful use of roles - and David's written a proposal to address that.
  • Mark Lentczner started a thread about the 7.10.2 release schedule - because this time, he wants to do a concurrent Haskell Platform release! The thread ended up with a good amount of discussion concerning if 7.10.2 is even needed - but at this rate, it looks like it will ship sometime soon.
  • Mateusz Kowalczyk posted to ghc-devs hoping to get some help with a tricky, long-standing issue: #4012, which concerns the determinism of GHC binaries. It turns out GHC isn't entirely deterministic when it calculates package IDs, meaning things get really bad when you mix prebuilt binary packages for systems. This in particular has become a real problem for the Nix package manager and users of Haskell applications. Mateusz asks if anyone would be willing to help look into it - and a lot of people would appreciate the help!

Noteworthy commits

Closed tickets

#10293, #10273, #10021, #10209, #10255, #10326, #9745, #10314, #8928, #8743, #10182, #10281, #10325, #10297, #10292, #10304, #10260, #9204, #10121, #10329, #9920, #10308, #10234, #10356, #10351, #10364, #9564, #10306, #10108, #9581, #10369, #9673, #10288, #10260, #10363, #10315, #10389, #9929, #10384, #10382, #10400, #10256, #10254, #10277, #10299, #10268, #10269, #10280, #10312, #10209, #10109, #10321, #10285, #9895, #10395, #10263, #10293, #10210, #10302, #10206, #9858, #10045, and #9840.

GHC Weekly News - 2015/04/14

Hi *,

It's been a few weeks since the last news bulletin - your editor apologizes about that. It's actually been a relatively slow few weeks here too, and busy-ness outside of GHC has attracted some of my attention. Despite that, GHC 7.10.1 was released, a new HP alpha is out, and things are moving along smoothly. Now that the release is done, things are quitely moving along in HEAD - with people committing code with reckless abandon, of course.

This week, GHC HQ met up, but it's been very light since the 7.10.1 release. Currently there isn't anything pushing us to do a 7.10.2 release at least for a few more weeks it looks like - but see below.

  • We puzzled a bit about the release status of 7.10.2, and thought: it's only holding up people who are depending on it. So, who's depending on it, and what do they need fixed? See below for more.
  • We also talked a bit about performance - it seems the compiler has been getting much slower over time since the 7.8.x release series, and it's time to reign it in. Austin will be spending his week investigating a bit of this, and the causes.

7.10.2 Status

So, you may be wondering when the 7.10.2 release is. The trick is it happens when you tell us it should happen!

So far, taking a look at milestone:7.10.2, we've fixed about half the bugs we currently have marked down to fix. But we're probably going to punt some of those - and we're not sure all the ones that are there should be.

So this is a call: If you need something to be fixed during 7.10.2, please file a ticket, set the milestone, and alert us. The sooner the better, because it'll inform us as to when we should release. Emailing is also a sure-fire way to get our attention.

And remember: you can always find out the latest about the next release at the Status page (in this case, for 7.10.2) -

Call for help: DocBook to AsciiDoc

The GHC team needs some help. A few months ago, we put out a poll to convert our DocBook-based manual to AsciiDoc.

The poll had a mostly lukewarm reception, with the idea that it will A) make life easier for people who frequently modify the users guide, and B) make life easier for people who add things irregularly, as a lower barrier to entry.

It looks like we still want to do this - but alas, many of us don't have time!

So, we're asking the public: Is anyone willing to step up and help here? For example, it may be possible to get a long ways with just pandoc, but we need someone to finish it - and in return, we'll help along the way!

List chatter

  • A GHC user, Dave, asked the list about some questions with Cross Compilation, as he's attempting to get GHC to work natively inside the Open Embedded build environment. Unfortunately, things haven't been going well so far, and any input from enterprising hackers is appreciated:
  • Dan Aloni has started a discussion about improving GHC's error messages, spurred by a popular blog post he wrote and posted on Reddit about some Happy/GHC improvements he's made. This is a difficult area (error messages in general are hard) to work on, so thanks to Dan for helping!
  • Tamar Christina started a thread about replacing ghc-split, an old Perl script inside GHC, but he wanted to know: what do we do about a regex replacement? Mikhail Glushenkov spoke up about a similar decision the LLVM developers used: to use the OpenBSD regex implementation.

Noteworthy commits

Closed tickets

#10222, #10219, #8057, #10226, #10220, #9723, #10230, #10208, #10236, #10213, #10231, #10240, #10243, #10237, #10224, #8811, #10197, #10252, #9958, #10253, #8248, #10207, #10214, #9964, #10194, #10251, #10188, #10257, #10247, #10247, #9160, #10259, #9965, #10265, #10264, #10286, #10282, #10290, #10291, #10300, #9929, #8276, #10218, #10148, #10232, #10274, #10275, #10195, and #10233.

GHC Weekly News - 2015/03/24

Hi *,

It's time for the GHC weekly news. We've had an absence of the last one, mostly due to a lot of hustle to try and get 7.10 out the door (more on that shortly throughout this post). But now we're back and everything seems to be taken care of.

This week, in the wake of the GHC 7.10 release (which is occuring EOD, hopefully), GHC HQ met up for a brief chat and caught up:

  • This week GHC HQ met for only a very short time to discuss the pending release - it looks like all the blocking bugs have been fixed, and we've got everything triaged appropriately. You'll hopefully see the 7.10 announcement shortly after reading this.

We've also had small amounts of list activity (the past 6-8 weeks have been very, very quiet it seems):

  • Yitzchak Gale revived a thread he started a while back, which puttered out: bootstrapping GHC 7.8 with GHC 7.10. The long and short of it is, it should just about work - although we still haven't committed to this policy, it looks like Yitz and some others are quite adamant about it.

Some noteworthy commits that went into ghc.git in the past two weeks include:

Closed tickets this past week include: #9122, #10099, #10081, #9886, #9722, #9619, #9920, #9691, #8976, #9873, #9541, #9619, #9799, #9823, #10156, #1820, #6079, #9056, #9963, #10164, #10138, #10166, #10115, #9921, #9873, #9956, #9609, #7191, #10165, #10011, #8379, #10177, #9261, #10176, #10151, #9839, #8078, #8727, #9849, #10146, #9194, #10158, #7788, #9554, #8550, #10079, #10139, #10180, #10181, #10170, #10186, #10038, #10164, and #8976.

GHC Weekly News - 2015/03/10

Hi *,

It's that time again! Today GHC HQ met on a Tuesday to avoid some scheduling conflicts, and that means it's time to send some news to people.

Just a quick reminder from last week: we're hoping to make our third GHC 7.10.1 release candidate on Friday, March 13th, with the final release on Friday, March 27th.

  • Today, GHC HQ mostly talked about 7.10 bugs; HEAD is steaming along as usual with no impediments, but we've got several critical bugs we plan on landing fixes for this week; see milestone:7.10.1 for more.

But we've also had a little more list activity this week than we did before:

  • Karel Gardas wrote to the list about how to better parallelize the GHC build. For background, he's using a UltraSPARC T1-CPU/T2000 server with 32 hardware threads over 8 cores, where parallelism is a bigger win than raw single-threaded performance. But despite that, the performance is of the parallel GHC build is relatively abysmal - and Karel wants help brainstorming ideas to fix it.

Some noteworthy commits that went into ghc.git in the past week include:

Closed tickets the past week include: #7854, #10118, #10119, #3321, #10132, #9987, #10126, #9707, #10142, #10147, #10113, #9524, #10058, #10100, #2991, #10140, and #9122.

GHC Weekly News - 2015/03/03

Hi *,

It's that time again! Today GHC HQ met on a Tuesday to avoid some scheduling conflicts, and that means it's time to send some news to people.

Just a quick reminder from last week: we're hoping to make our third GHC 7.10.1 release candidate on Friday, March 13th, with the final release on Friday, March 27th.

Today, GHC HQ met up and mostly discussed the current status of GHC 7.10 and its bugs, which you can find on the Status page:

But we've also had a little more list activity this week than we did before:

Some noteworthy commits that went into ghc.git in the past week include:

Closed tickets the past week include: #9586, #10122, #10026, #8896, #10090, #10123, #10128, #10025, #10024, #10125, #9994, #9962, #10103, #10112, #10122, #9901, #10130, #10129, #9044, #8342, #8780, #10003, #17, #2530, #8274, and #10107.

GHC Weekly News - 2015/02/23

Hi *,

It's once again time for your sometimes-slightly-irregularly-scheduled GHC news! This past Friday marked the end of the FTP vote for GHC 7.10, there's an RC on the way (see below), we've closed out a good set of patches and tickets from users and pushed them into HEAD, and to top it off - it's your editor's birthday today, so that's nice!

Quick note: as said above GHC HQ is expecting to make a third release candidate for GHC 7.10.1 soon in early March since the delay has allowed us to pick up some more changes and bugfixes. We plan on the final release being close to the end of March (previously end of February).

This week, GHC HQ met up again to discuss and write down our current priorities and thoughts:

  • After discussing our current timetable - as we're currently hovering around the ICFP deadline - we're hoping to make our third GHC 7.10.1 release candidate on Friday, March 13th, with the final release on Friday, March 27th. This was the main take away from our meeting today.

We've also had a little more list activity this week than we did before:

Some noteworthy commits that went into ghc.git in the past week include:

Closed tickets the past week include: #9266, #10095, #9959, #10086, #9094, #9606, #9402, #10093, #9054, #10102, #4366, #7604, #9103, #10104, #7765, #7103, #10051, #7056, #9907, #10078, #10096, #10072, #10043, #9926, #10088, #10091, #8309, #9049, #9895, and #8539.

GHC Weekly News - 2015/02/17

Hi *,

It's time for the GHC weekly news. It's been particularly quiet the past week still, and the ghc-7.10 branch has been quite quiet. So the notes are relatively short this week.

This week, GHC HQ met up to discuss some new stuff:

  • Most of the discussion this week was about particular bugs for GHC 7.10, including getting some tickets fixed like #10058, #8276, and #9968.
  • Since the 7.10 release is getting close, we'll be starting up a new status page about GHC 7.12 (and probably get started writing things for the HCAR report in May) and what our plans are soon. Watch this space!

As usual, we've had a healthy amount of random assorted chatter on the mailing lists:

Some noteworthy commits that went into ghc.git in the past week include:

Closed tickets the past week include: #10047, #10082, #10019, #10007, #9930, #10085, #10080, #9266, #10095, and #3649.

GHC Weekly News - 2015/02/10

Hi *,

Welcome! This is the first GHC Weekly news of February 2015. You might be wondering what happened to the last one. Well, your editor was just in New York for the past week attending Compose Conference, making friends and talking a lot about Haskell (luckily we missed a snow storm that may have messed it up quite badly!)

The conference was great. I got to have some interesting discussions about GHC and Haskell with many friendly faces from all around at an incredibly well run conference with a stellar set of people. Many thanks to NY Haskell (organizing), Spotify (hosting space), and to all the speakers for a wonderful time. (And of course, your editor would like to thank his employer Well-Typed for sending him!)

But now, since your author has returned, GHC HQ met back up this week for some discussion, with some regularly scheduled topics. For the most part it was a short meeting this week - our goals are pretty well identified:

  • It's likely GHC HQ will do a third 7.10.1 Release Candidate at the very end of February after the votes are included. We missed some patches in RC2 (such as Phab:D347) and incorporated even more bugfixes, so this is worth a test drive by users.
  • For the most part, things for 7.10 have been going very smoothly other than the debates and a few bugs trickling in - there has not been much ticket activity the past two weeks, so things feel pretty good right now. Austin will mostly be focused on shipping 7.10 and keeping the normal review/patch/triaging cycles going until it's done. We're on track to fix all the major bugs we've assigned (see milestone:7.10.1).

Since my last post, we've also had other random assorted chatter on the mailing lists by the dev team:

  • In light of a recent large bug in GHC which can be used to derive unsafeCoerce, GHC HQ has decided to push back the 7.10 release a bit longer to about March, in order to fix this bug and ferret out the little fallout afterwords. It turns out this isn't a simple bug to fix, but luckily a fix is being worked on already.
  • David Feuer has a question: why is undefined so special? In particular, it seems as if undefined can be specially used as a value with a type of kind # as well as *. It turns out GHC has a special notion of subkinding, and undefined has a type more special than meets the eye which allows this, as Adam Gundry replied.
  • Greg Weber opened up a discussion about 'Restricted Template Haskell', which would hopefully make it easier for users to see what a TH computation is actually doing. It turns out - as noted by Simon - that Typed Template Haskell is perhaps closer to what Greg wants. The proposal and discussion then resulted in us realising that the typed TH documentation is rather poor! Hopefully Greg or someone can swing in to improve things.

Closed tickets the past two weeks include: #10028, #10040, #10031, #9935, #9928, #2615, #10048, #10057, #10054, #10060, #10017, #10038, #9937, #8796, #10030, #9988, #10066, #7425, #7424, #7434, #10041, #2917, #4834, #10004, #10050, #10020, #10036, #9213, and #10047.

GHC Weekly News - 2015/01/27

Hi *,

It's time for some GHC Weekly news!

  • Austin took the time the past week to check `./validate --slow` failures, and is planning on filing bugs and fixes for the remaining failures soon. Afterwords, we'll immediately begin enabling --slow on Phabricator, so developers get their patches tested more thoroughly.
  • The 7.10 release looks like it will likely not have a 3rd Release Candidate, and will be released in late Feburary of 2015, as we originally expected.
  • The 7.10 branch currently has two showstopping bugs we plan on hitting before the final release. And we'd really like for users to test so we can catch more!
  • Austin Seipp will likely be gone for the coming week in a trip to New York City from the 28th to the 4th, meaning (much to the dismay of cheering crowds) you'd better catch him beforehand if you need him! (Alternatively Austin will be held back due to an intense snowstorm developing in NYC. So, we'll see!)
  • Austin is planning on helping the LLVM support in HEAD soon; after coordinating with Ben Gamari, we're hoping to ship GHC 7.12 with (at least) LLVM 3.6 as an officially supported backend, based on the documentation described in - lots of thanks to Ben for working with upstream to file bugs and improve things!

And in other news, through chatter on the mailing list and Phabricator, we have:

  • Peter Trommler posted his first version of a native Linux/PowerPC 64bit code generator! There's still a lot more work to do, but this is a significantly improved situation over the unregisterised C backend. Curious developers can see the patch at Phab:D629.
  • A long, ongoing thread started by Richard Eisenberg about the long-term plans for the vectorisation code have been posted. The worry is that the vectoriser as well as DPH have stagnated in development, which costs other developers any time they need to build GHC, make larger changes, or keep code clean. There have been a lot of varied proposals in the thread from removing the code to commenting it out, to keeping it. It's unclear what the future holds, but the discussion still rages on.
  • Alexander Vershilov made a proposal to the GHC team: can we remove the transformers dependency? It turns out to be a rather painful dependency for users of the GHC API and of packages depending on transformers, as you cannot link against any version other than the one GHC ships, causing pain. The alternative proposal involves splitting off the transformers dependency into a package of Orphan instances. The final decision isn't yet clear, nor is a winner in clear sight yet!
  • Simon Marlow has started a long thread about the fate of records in future GHC versions. Previously, Adam Gundry had worked on OverloadedRecordFields. And now Nikita Volkov has introduced his records library which sits in a slightly different spot in the design space. But now the question is - how do we proceed? Despite all prior historical precedent, it looks like there's finally some convergence on a reasonable design that can hit GHC in the future.

Closed tickets the past two weeks include: #9889, #9384, #8624, #9922, #9878, #9999, #9957, #7298, #9836, #10008, #9856, #9975, #10013, #9949, #9953, #9856, #9955, #9867, #10015, #9961, #5364, #9928, and #10028.

GHC Weekly News - 2015/01/19

Hi *,

It's time for some more GHC news! The GHC 7.10 release is closing in, which has been the primary place we're focusing our attention. In particular, we're hoping RC2 will be Real Soon Now.

Some notes from the past GHC HQ meetings this week:

  • GHC 7.10 is still rolling along smoothly, and it's expected that RC2 will be cut this Friday, January 23rd. Austin sent out an email about this to ghc-devs, so we can hopefully get all the necessary fixes in.
  • Currently, GHC HQ isn't planning on focusing many cycles on any GHC 7.10 tickets that aren't highest priority. We're otherwise going to fix things as we see fit, at our leisure - but a highest priority bug is a showstopper for us. This means if you have something you consider a showstopper for the next release, you should bump the priority on the ticket and yell at us!
  • We otherwise think everything looks pretty smooth for 7.10.1 RC2 - our libraries are updated, and most of the currently queued patches (with a few minor exceptions) are done and merged.

Some notes from the mailing list include:

  • Austin has alerted everyone that soon, Phabricator will run all builds with ./validate --slow, which will increase the time taken for most builds, but will catch a wider array of bugs in commits and submitted patches - there are many cases the default ./validate script still doesn't catch.
  • Johan Tibell asked about some clarifications for the HsBang datatype inside GHC. In response, Simon came back with some clarifications, comments, and refactorings, which greatly helped Johan. ttps://
  • Richard Eisenberg had a question about the vectoriser: can we disable it? DPH seems to have stagnated a bit recently, bringing into question the necessity of keeping it on. There hasn't been anything done yet, but it looks like the build will get lighter, with a few more modules soon:
  • Jan Stolarek has a simple question: what English spelling do we aim for in GHC? It seems that while GHC supports an assortment of British and American english syntactic literals (e.g. SPECIALIZE and SPECIALISE), the compiler sports an assortment of British/American identifiers on its own!

Closed tickets the past few weeks include: #9966, #9904, #9969, #9972, #9934, #9967, #9875, #9900, #9973, #9890, #5821, #9984, #9997, #9998, #9971, #10000, #10002, #9243, #9889, #9384, #8624, #9922, #9878, #9999, #9957, #7298, and #9836.

GHC Weekly News - 2015/01/07

Hi *, it's time for another GHC Weekly News! This week's edition will actually be covering the last two/three weeks; your editor has missed the past few editions due to Holiday madness (and also some relaxation, which is not madness). It's also our first news posting in 2015!

So let's get going without any further delay!

GHC HQ met this week after the Christmas break; some of our notes include:

  • Since Austin is back, he'll be spending some time finishing up all the remaining binary distributions for GHC 7.8.4 and GHC 7.10.1 RC1 (mostly, FreeBSD and OS X builds).
  • We've found that 7.10.1 RC1 is working surprisingly well for users so far; to help users accomodate the changes, Herbert has conveniently written a migration guide for users for their most common problems when upgrading to 7.10.1:
  • We're aiming to release the 2nd Release Candidate for GHC 7.10.1 on January 19th. We're hoping this will be the last RC, with 7.10.1 final popping up in the middle of February.
  • GHC HQ may tentatively be working to release another GHC 7.8 release, but only for a specific purpose: to allow it to compile with 7.10.1. This will make it significantly easier for users to compile old GHCs (perhaps on newer platforms). However, we're not yet 100% decided on this, and we will likely only do a 'very minor release' of the source tarball, should this be the case. Thanks to Edward Yang for helping with this.
  • For future GHC releases on Windows, we're looking into adopting Neil Mitchell's new binary distribution of GHC, which is a nice installer that includes Cabal, MSYS and GHC. This should significantly lower the burden for Windows users to use GHC and update, ship or create packages. While we're not 100% sure we'll be able to have it ready for 7.10.1, it looks promising. Thanks Neil! (For more info, read Neil's blog post here: )

There's also been some movement and chatter on the mailing lists, as usual.

  • Joachim Breitner made an exciting announcement: he's working on a new performance dashboard for GHC, so we can more easily track and look at performance results over time. The current prototype looks great, and Joachim and Austin are working together to make this an official piece of GHC's infrastructure:
  • Over the holiday, Simon went and implemented a nice new feature for GHC: detection of redundant constraints. This means if you mention Ord in a type signature, but actually use nothing which requires that constraint, GHC can properly warn about it. This will be going into 7.12:
  • Now that GHC 7.10 will feature support for DWARF based debugging information, Johan Tibell opened a very obvious discussion thread: what should we do about shipping GHC and its libraries with debug support? Peter chimed in with some notes - hopefully this will all be sorted out in time for 7.10.1 proper:

Closed tickets the past few weeks include: #8984, #9880, #9732, #9783, #9575, #9860, #9316, #9845, #9913, #9909, #8650, #9881, #9919, #9732, #9783, #9915, #9914, #9751, #9744, #9879, #9876, #9032, #7473, #9764, #9067, #9852, #9847, #9891, #8909, #9954, #9508, #9586, and #9939.

GHC Weekly News - 2014/12/16

Hi *, time for another piece of the GHC weekly news!

  • For the past few days, Richard Eisenberg has been hunting a performance regression in the compiler. After profiling, discussion on IRC and elsewhere, Richard has finally made some headway, and discovered one of the 'hot spots' in his patch. Unfortunately the battle isn't quite over just yet, and the hunt for a few more % increase remains.

Finally, in a slight change, we'll also be covering some notes from this week's meeting between GHC HQ (Austin, Simon PJ, SimonM, Herbert and Mikolaj), including...

  • The 7.10 RC1 looks like it's scheduled to occur this week still; all of our libraries and submodules are up-to-date, and we've taken the time to alert all of our maintainers about this. Thanks to Herbert for taking control of this!
  • We'll soon be implementing a new 'push hook' for the ghc.git repository: no more trailing whitespace. Since we've recently detabbed, and de-lhs-ified the tree, a knock-on effect was deleting trailing whitespace. Now that we've done a lot of this, we should take the time to enforce it - so they can't slip back in.
  • This week, Austin managed to secure two sponsors for GHC/ We've been given a wonderful set of ARM buildbots (running in the cloud!) and a new, incredibly powerful POWER8 machine to use (with over 170 hardware threads available, for scalability testing). Hooray for our friends at and for helping us out!

Closed tickets this week include: #9871, #9808, #9870, #9605, #9874, #9872, #9090, #9404, #8240, #9567, #9566, #9583, #9117, #9882, #9884, #9372, #7942, #8951, #9817, #9620, #9336, #9523, #9552, #8988, #9390, #9415, #9371, #7143, #9563, #8778, #4428, #4896, #9393, #9169, #7015, #8943, #8621, #9132, #9857, #8024, #9831, and #9888.

GHC Weekly News - 2014/12/08

Hi *,

Once more, it's time for some news about GHC! This week's regularly scheduled programming (get it?) has brought you...

Closed tickets this week include: #9850, #9005, #9828, #9833, #9582, #8935, #9186, #9480, #9497, #7908, #4347, #3977, #3859, #3844, #3814, #3771, #3739, #2182, #9812, #4921, #7947, #9240, #5401, #3625, #3517, #9444, #9142, #3447, #8894, #3065, #3191, #2697, #2836, #5443, #7736, #2489, #2456, #2204, #9777, #9859, #9869, #9808

GHC Weekly News - 2014/12/01

Hi *,

It's that time again for some good ol' fashion GHC news, this time just after the holidays. Some of the things happening in the past week include:

  • Partial Type Signatures has been merged into HEAD. Many thanks to Thomas Winant, who worked on this feature for several months!
  • As mentioned last week, GHC 7.10 will no longer ship haskell98 and haskell2010, nor old-time or old-locale.

Closed tickets this week include: #9827, #7475, #9826, #7460, #7643, #8044, #8031, #7072, #3654, #7033, #9834, #6098, #6022, #5859, #5763, #9838, #9830, #7243, #9736, #9574, #5158, #9844, #9281, #9818, #4429, #8815, #2182, #4290, #9005, #9828, #9833, #9582, and #9850.

Another huge thanks to Thomas Miedema who closed an extraordinary amount of tickets for us - the above list is still not even complete, and he's made a huge impact on the amount of open tickets in the past month or so.

GHC Weekly News - 2014/11/21

Hi *,

To get things back on track, we have a short post following up the earlier one this week. It's been busy today so I'll keep it short:

  • The STABLE freeze Austin announced two weeks ago is happening now, although at this point a few things we wanted to ship are just 98% ready. So it may wait until Monday.
  • HEAD has been very busy the past two days as many things are now trying to merge as closely to the window as possible. Some notes follow.
  • HEAD now has support for using the 'deriving' clause for arbitrary classes (see #5462).
  • HEAD now has 64bit iOS and SMP support for ARM64, thanks to Luke Iannini. See #7942.
  • base now exports a new module for Natural numbers called Numeric.Natural following Herbert Valerio Riedel's recent proposal.
  • Your author has been busy and delayed due to some bad travel experiences the past week, so the 7.8.4 RC1 hasn't landed this past week. Hopefully it will be out by the end of this week still.

Since the last update was only a few days ago, you'd think we haven't closed a lot of tickets, but we have! Thomas Miedema has been very very persistent about closing tickets and cleaning them up, which is greatly appreciated: #9810, #8324, #8310, #9396, #9626, #9776, #9807, #9698, #7942, #9703, #8584, #8968, #8174, #9812, #9209, #9220, #9151, #9201, #9318, #9109, #9126, #8406, #8102, #8093, #8085, #8068, #8094, #9590, #9368, #2526, #9569, #8149, #9815, #5462, #9647, #8568, #9293, #7484, #1476, #9824, #9628, #7942

GHC Weekly News 2014/11/18

Hello *,

Once more we have the GHC Weekly news! This one is a bit late due to Austin being in limbo unexpectedly for a few days last week. (The next one will of course come again on Friday to keep things straight.)

With that out of the way, let's see what exactly is going on:

  • The STABLE freeze is happening at the end of this week! That means if you have something you want to get in, try to get people aware of it! Austin (yours truly) has a backed up review queue it would seem, but hopes to clear a bunch of it out before then.
  • Herbert Valerio Riedel has finally landed integer-gmp2, AKA Phab:D86, which implements a complete overhaul of the integer-gmp library. This library will be switched on by default in GHC 7.10.1, which means the integer-gmp library version will have a super-major bump (version This is the beginning of a longer-term vision for more flexible Integer support in GHC, as described by Herbert on the design page: This implementation also fixes a long standing pain point where GHC would hook GMP allocations to exist on the GHC heap. Now GMP is just called to like any FFI library.
  • Jan Stolarek made a heads up to help out GHC newcomers: if you see a ticket that should be easy, please tag it with the newcomer keyword! This will let us have a live search of bugs that new developers can take over. (Incidentally, Joachim mentions this is the same thing Debian is doing in their bug tracker):
  • Adam Gundry, Eric Seidel, and Iavor Diatchki have grouped together to get a new, unexpected feature into 7.10: type checking plugins. Now, GHC will be able to load a regular Haskell package as a plugin during the compilation process. Iavor has a work-in-progress plugin that solves constraints for type-level natural numbers using a SMT solver. The code review from everyone was published in Phab:D489.

Closed tickets this week include: #9785, #9053, #9513, #9073, #9077, #9683, #9662, #9646, #9787, #8672, #9791, #9781, #9621, #9594, #9066, #9527, #8100, #9064, #9204, #9788, #9794, #9608, #9442, #9428, #9763, #9664, #8750, #9796, #9341, #9330, #9323, #9322, #9749, #7381, #8701, #9286, #9802, #9800, #9302, #9174, #9171, #9141, #9100, #9134, #8798, #8756, #8716, #8688, #8680, #8664, #8647, #9804, #8620, #9801, #8559, #8559, #8545, #8528, #8544, #8558

GHC Weekly News - 2014/11/07

Hello *,

It's that time again, so get ready for some good ol' fashion news about your favorite compiler.

And this weeks closed tickets include quite a long list, thanks to everyone cleaning up the bug tracker: #9747, #9236, #9753, #9752, #9262, #8953, #9084, #9738, #8571, #8295, #8261, #9754, #110, #9345, #8849, #8819, #9658, #8960, #9395, #9705, #9433, #9633, #9359, #9081, #8482, #3376, #9712, #9739, #9211, #9728, #9750, #9768, #9773, #9741, #9284, #9774, #9771, #9001, #8626, #8986, #9268, #8975, #8962, #8921, #8089, #8843, #8829, #9295, #7913, #2528, #9779.

GHC Weekly News - 2014/10/31 (Halloween Edition)

Hello *,

Welcome to the GHC Weekly news. And it's just in time before you go out and eat lots of candy and food.

  • David Feuer and Joachim Brietner spent some time this past week talking about more optimizations for Haskell code for fusing code, and creating better consumers and producers. This work includes optimizations of "One shot lambdas" (lambdas used at most once) and Call Arity, which was implemented by Joachim at Microsoft Research. The thread is here -

The current situation is that Call Arity and One shot analysis tends to have good combined results for exploiting more fusion opportunities, but sometimes these backfire. As a result, Joachim and David have worked on improving the situation - particularly by letting programmers help with a new oneShot primitive (in Phab:D392 & Phab:D393).

  • Herbert Valerio Riedel opened up a discussion about the origins of code contributions. In short, we'd like to have some stronger ground to stand on in the face of contributions from contributors - the origin of a change and its legal status is a bit nebulous. The thread is here:

Overall, there's been a lot of separate points made, including CLAs (unlikely), "Developer Certificates of Origin" a la the Linux Kernel, and reworking how we mark up header files, and keep track of GHC's long history of authors. If you work on a big project where some of these concerns are real, we'd like to hear what you have to say!

  • Gintautas Milauskas has done some fantastic work for GHC on Windows lately, including fixing tests, improving the build, and making things a lot more reasonable to use. With his work, we hope GHC 7.10 will finally ship an updated MinGW compiler (a long requested feature), and have a lot of good fixes for windows. Thank you, Gintautas!
  • And on that note, the call for Windows developers rages on - it looks like Gintautaus, Austin, Simon, and others will be meeting to discuss the best way to tackle our current woes. Are you a Windows user? Please give us input - having input is a crucial part of the decision making process, so let us know.
  • Jan Stolarek had a question about core2core - a lot of questions, in fact. What's the difference between demand, strictness, and cardinality analylsis? Does the demand analyzer change things? And what's going on in some of the implementation? A good read if you're interested in deep GHC optimization magic:
  • Peter Wortmann has put up the new DWARF generation patches for review, in Phab:D396. This is one of the major components we still plan on landing in 7.10, and with a few weeks to spare, it looks like we can make sure it's merged for the STABLE freeze!
  • There have been a lot of good changes in the tree this past week:

Thanks to Michael Orlitzky, we plan on adding doctest examples to more modules in 7.10, and increase that coverage further. This is *really* important work, but very low fruit - thanks a ton Michael!

Data.Bifunctor is now inside base! (Phab:D336)

atomicModifyIORef' has been optimized with excellent speedups (as much as 1.7x to 1.4x, depending on the RTS used), thanks to some older work by Patrick Palka (Phab:D315). GHC's internals have been reworked to unwire Integer from GHC, leading not only to a code cleanup, but laying the foundation for further GMP (and non-GMP!) related Integer improvements (Phab:D351).

David Feuer and Joachim have been relentless in improving fusion opportunities, including the performance of take, isSuffixOf, and more prelude improvements, spread over nearly half a dozen patches. And this doesn't even include the work on improving oneShot or Call Arity!

In a slight change to base semantics, David Feuer also finally fixed #9236. This is a change that can expose latent bugs in your program (as it did for Haddock), so be sure to test thoroughly with 7.10 (Phab:D327).

GHC now has support for a new __GLASGOW_HASKELL_TH__ macro, primarily useful for testing bootstrap compilers, or compilers which don't support GHCi.

And there have been many closed tickets: #9549, #9593, #9720, #9031, #8345, #9439, #9435, #8825, #9006, #9417, #9727, #2104, #9676, #2628, #9510, #9740, #9734, #9367, #9726, #7984, #9230, #9681, #9747, and #9236.

GHC Weekly News - 2014/10/24

Hi *,

Welcome to the weekly GHC news. This one will be short this week, as the preceding one occurred only on Monday - but we'll be going with Fridays from now on, so next week we'll hopefully see a longer list.

  • GHC 7.8.4 tickets have been in waiting, and the RC will be soon after Austin finishes some final merges and tests on his branch. We have not committed a time for the release after the RC, yet we would like people to please seriously test and immediately report any major showstoppers - or alert us of ones we missed.
  • For the GHC 7.10 release, one of the major features we planned to try and merge was DWARF debugging information. This is actually a small component of larger ongoing work, including adding stack traces to Haskell executables. While, unfortunately, not all the work can be merged, we talked with Peter, and made a plan: our hope is to get Phab:D169 merged, which lays all the groundwork, followed by DWARF debugging information in the code generators. This will allow tools like gdb or other extensible debuggers to analyze C-- IR accurately for compiled executables. Peter has written up a wiki page, available at SourceNotes, describing the design. We hope to land all the core infrastructure in Phab:D169 soon, followed by DWARF information for the Native Code Generator, all for 7.10.1
  • This past week, a discussion sort of organically started on the #ghc IRC channel about the future of the LLVM backend. GHC's backend is buggy, has no control over LLVM versions, and breaks frequently with new versions. This all significantly impacts users, and relegates the backend to a second class citizen. After some discussion, Austin wrote up a proposal for a improved backend, and wrangled several other people to help. The current plan is to try an execute this by GHC 7.12, with the goal of making the LLVM backend Tier 1 for major supported platforms.
  • You may notice is now responds slightly faster in some cases - we've activated a caching layer (CloudFlare) on the site, so hopefully things should be a little more smooth.

Closed tickets this week: #9684, #9692, #9038, #9679, #9537, #1473.

GHC Weekly News - 2014/10/20

Hi *,

It's been a few weeks since the last message - and I apologize! We actually are changing the posting time to be Friday now, so hopefully this situation will be corrected preeeeetty quickly from this point forward, and hopefully will give better context over the course of a weekly discussion.

That said, let's begin!

  • We've seen plenty of changes to GHC itself in the past few weeks. Some of the highlights include:
    • Some changes to help make Prelude combinators fuse better. David Feuer has been leading a lot of this work, and it's been quite fruitful, with several new things now fusing (like takeWhile, scanl, scanr, and mapAccumL.
    • Relatedly, Data.List.Inits should be far faster thanks to David Feuer (ref: Phab:D329).
    • The testsuite driver now has preliminary support for Python 3 - which should be useful for platforms out there that sport it, and ones that will use it as the default eventually (such as Fedora 22, possibly).
    • Some of the initial work by Edward Yang to remove HEAP_ALLOCED from the GHC runtime system has landed. Briefly, HEAP_ALLOCED is a check the RTS uses to determine if some address is part of the dynamic heap - but the check is a bit costly. Edward's full patchset hopes to remove this with an 8% speedup or so on average.
    • GHC now has a new macro, __GLASGOW_HASKELL_PATCHLEVEL__, which will allow you to determine the point-level release of the GHC you're using. This has been a requested feature in the past we were a little hesitant of adding, but Herbert went through and did it for us. (Ref: Phab:D66)
    • Template Haskell now supports LINE pragmas, thanks to Eric Mertens (ref: Phab:D299).
    • Sergei Trofimovich revived libbfd debugging support for the runtime system linker, which should be of use to several daring souls out there (ref: Phab:D193).
    • Several patches from Gintautas Miliauskas has improved the usability of msys and the testsuite on Windows - and he's not done yet!
    • A few improvements to the x86 code generator were committed by Reid Barton and Herbert Valerio Riedel, improving size/space for certain cases (ref: Phab:D320, Phab:D163).

and more besides that, including some linker improvements, and general cleanups as usual.

  • The mailing list has been busy (as usual), with some discussions including:
    • Austin posted some discussion about the tentative 7.10.1 plans - we're still hoping these are accurate, so take note! We hope to freeze mid-November, and release Feburary 2015! [1]
    • Austin also called for some feedback: GHC HQ has become convinced a 7.8.4 release is needed to fix some showstoppers - so please let him know soon if you're totally incapable of using 7.8 for something! [2]
    • Alan Zimmerman has asked for some feedback on his proposed "AST Annotations", which will hopefully allow GHC API clients to add richer annotations to GHC's syntactic representations. The motivation is for refactoring tools like HaRe - and I'm sure all input would be appreciated. [3]
    • Chris done sparked off a discussion about making GHCi awesomer, and I'm sure everyone can appreciate that! In particular, Chris wanted to discuss programmatic means of controlling GHCi itself, and naturally we need to ask - is the current API not enough, and why? [4]
    • Yuras Shumovich has implemented a proposal for allowing the Haskell FFI to support C structures natively as return values - this involves interfacing with C ABI rules to properly support structure layout. While Yuras has an initial implementation in Phab:D252, some questions about the feature - including its implementation complexity - remain before it gets merged. [5]
    • Richard Eisenberg made a modest request: can Phabricator patches have a 'roadmap', so people can instruct reviewers how to read a diff? The answer: yes, and it should be relatively easy to implement, and Austin can do so Real Soon Now™. [6]
    • Ben Gamari started a big discussion about one-shot event semantics in the I/O manager, with a lot of replies concerning not only the bug, but machines to test the actual change on. With any luck, Ben's fix for the I/O manager and a test machine should come quickly enough. [7]
    • Herbert Valerio Riedel opened an RFC: Should we look into using AsciiDoc for GHC? Historically, GHC's documentation has been written using DocBook, a verbose but very precise and unambiguous documentation format. However, AsciiDoc offers a much nicer markup language, while retaining DocBook support. In short, it looks like GHC may get a much more clean user manual soon. [8]
    • Yuras opened another discussion: Should we namespace proposals we create on our wiki? What seems uncontroversial can lead to surprising discussion, and the results were mixed this time it seems. [9]
    • Geoff Mainland stepped up and fixed Data Parallel Haskell to work with a new version of vector and GHC. Austin had disabled DPH a few weeks prior due to its difficulty to upgrade, and divergent source trees. With 7.10, GHC will hopefully ship a more modern vector and dph to boot.
    • Austin asks: can we warn on tabs by default for GHC 7.10? It's an easy change and a minor one - but we should at least ask first. Vote now! [10]
    • Philip Hölzenspies opens up a discussion about Uniques in GHC, and their impact on the compilers current design. Philip has a hopeful design to redo Unique values in GHC, and a patch to support it: Phab:D323. [11]
    • Richard Eisenberg asks: can we somehow integrate GitHub into our development process? While GitHub doesn't have as many nice tools as something like Phabricator, it has a very high inertia factor, and Richard is interested in making the 'first step' as easy as possible for newbies. Discussions about Phab<->GitHub integrations were afoot, as well as general discussion about contributor needs. There were a lot of points brought up, but the conversation has slightly dried up now - but will surely be revived again. [12]

And now, look at all these tickets we closed! Including: #9658, #9094, #9356, #9604, #9680, #9689, #9670, #9345, #9695, #9639, #9296, #9377, #9184, #9684.


GHC Weekly News - 2014/09/30

Hi *,

Here's some news for y'all! Apologizes about the unavailability last week; the internet wasn't exactly a very fun place for a system administrator...

So without delay, here's the current recap of the past two weeks:

  • Lots of merged code and code reviews have gone in, and a lot of commits: in the past two weeks since the last update, ghc.git has seen just over 100 commits, from about a dozen different developers.
  • As part of those patches, a significant amount of them have gone towards implementing the "Burning Bridges Proposal" or BBP for the base library. This is a set of changes to base that have generalized many parts of the API, by putting Traversable and Foldable in the Prelude. This required a bit of shoveling by Herbert, but now this is all in GHC HEAD, and will be part of 7.10:
    • Prelude combinators, like mapM, have been generalized to the Traversable and Foldable classes.
    • Several other modules, like Control.Monad and Data.List, have been generalized to Traversable and Foldable where applicable.
    • Control.Monad combinators generalized to Applicative where possible.
    • Similarly, MonadPlus combinators like guard are generalized to Alternative.
    • Foldable has been extended with new methods, like length and null.
  • But also, GHC's compiler is now tab-free! That's right, after what seemed like a million years, a very large portion of the code has been detabbed, and -fwarn-tabs is now on by default in the GHC build.
  • There are an assortment of other changes: GHC's linker is not as loud[1], and various documentation improvements.
  • The windows build is broken *again* unfortunately, this time due to what seems to be a Cabal update, I think. Austin is once again on the case.
  • The HCAR draft for October has seen some nice improvements. If you're a developer, please amend things. If you're a user, read with eager anticipation of all the new features![2]
  • It turns out the new Applicative/Monad changes have unfortunately broken the haskell98 and haskell2010 packages, with an unclear migration strategy for the future: see #9590. For GHC 7.10, it seems the haskell2010 packages will need to change to accomodate these standard deviations. If any users of the haskell98 or haskell2010 packages would speak up to help, that would be fantastic. The discussion will surely continue for a little bit - 7.10 is still a ways off.

In miscellaneous news:

  • may have been temporarily unavailable during this weekend due to an emergency downtime with our provider for a security update, but the window was quite small.
  • Relatedly (but not the exact same scenario), the internet also caught fire in several other places, requiring quite a lot of careful watching and remediation after the Bash "ShellShock" bug hit last week.

And I think that sums it up quite nicely, folks!

Closed tickets for the past two weeks include (there are a lot of them!): #9650, #7068, #5190, #5880, #8374, #9603, #3303, #3470, #3509, #781, #8115, #9641, #9191, #9515, #9326, #7987, #9634, #9576, #9612, #9635, #8593, #7544, #8529, #9338, #5794, #9535, #3646, #617, #8026, #8480, #8881, #9366, #8251, #7673, #8983, #8369, #8897, #8070, #9550, #9057, #9629, #8836, #8960, #8941, #9565, #9589, #5248, #8918, #9568, #9620, #1042, #9557, #7863, #5647, #9610, #5395, #9580, #9529, #4426, #9607, #9592, #8097, #9559, #9560, #4218, #9602, #9528, #9530, #9423, #9400, #1407, #9598, #9597.

I'd like to mention that for the above tickets, a *huge* amount of them were closed by one of our newest contributors, Thomas Miedema, who went through the bug tracker and confirmed or closed a large majority of them. I lost track of how many. Thanks Thomas!


GHC Weekly News - 2014/09/15

Hi *,

Here's a new thing: Blog posts! That's right. A while back, we started a new set of emails on the developers list containing weekly updates, from GHC HQ. But we eventually decided it should be more broad and encompass the work GHC sees as a project - including all the things our contributors do.

So now it's the weekly GHC news - and we (or, well, I) have decided to blogify the weekly emails!

So without further adieu, here's the current recap. The original mailing list copy is available here.

  • As Gabor mentioned on the list earlier today, I (Austin) accidentally broke the Windows build. Sorry. :( We really need to get Phab building Windows too ASAP... I'm working on a fix this morning.
  • I sent out the HCAR draft this morning. Please edit it! I think we have a few weeks of lead time however, so we're not in a rush like last time. But I will send reminders. :)
  • The server migration for seems to have gone pretty smoothly in the past week. It's had plenty of traffic so far. The full migration is still ongoing and I want to complete it this week.
  • I've finished reorganizing some of the Git and Repository pages after some discussion. We now have the Repositories[1] page, linked to on the left side, which details some notes on the repositories we use, and links to other various pages. I'm thinking of replacing this side-bar "root" with a link to the main Git[2] page, perhaps.
  • Miscellaneous: and now sets the Strict-Transport-Security header. This just means you always use SSL now when you visit those pages (so you can't be connection-hijacked via a 503 redirect).
  • GHC works on Wine apparently for all you Linux users - thanks Mikolaj![3]
  • Jan had some questions about infrastructure which I just followed up on this morning. In particular: does anyone feel strongly about his first question?[4]
  • Herbert committed the first part of the Traversable/Foldable changes, by moving the typeclasses to Prelude. This is part of an ongoing series of patches. Things like adding Bifunctor will finally come after this.[5]

Also, added bonus: we'll start including some of the tickets we closed this week.

Closed tickets for the past week include: #9585, #9545, #9581, #6086, #9558, and #3658.

Please let me know if you have any questions.