GHC on Windows (extended/broad discussion)

Gintautas Miliauskas gintautas at
Tue Oct 28 16:07:46 UTC 2014

Hey Austin,

thanks for pushing this forward. It sure looks like Windows deserves more
attention than it is getting.

We definitely need a broader action plan. My thoughts were close to yours:

1. Push through the gcc compiler upgrade (D339)
2. Fix the Windows continuous builds. This is necessary to prevent
3. Make sure results are clean on Windows. Tests that are known
to be failing are not providing new information, they should be disabled
and issues filed.
4. Triage the Windows bug list. I already made a few passes, but most of
the bugs are far from trivial. I think we'll need to prioritize very
aggressively to focus the limited resources.

Are there any broader ideas for architecture-level changes related to GHC
on Windows?

The people problem is tricky. At work, this would be the right time to do a
video chat and at least see the faces of the other people involved. Would
folks be interested in a Skype/Hangout sometime? It would be interesting to
hear what interests / skills / resources / constraints we have between us.

On Sat, Oct 25, 2014 at 2:24 AM, Austin Seipp <austin at> wrote:

> Gintautas, Tamar, Roman,
> (CC'ing those on
>, and Kyrill,
> who has helped us out much in the past)
> Thank you all for all your help with Windows recently. I apologize for
> not responding to some of your concerns sooner in the recent threads
> about tarballs, etc.
> First off, all your contributions are extremely welcome - GHC has had
> many talented Windows hackers in days long past, but these days this
> number has dwindled! Anyone who has an interest in GHC on Windows is
> in a place to make a big impact and help us. All the work Gintautas
> has done for example, will dramatically improve the ghc-tarballs
> scenario.
> On that note: Gintautas, I will get D339 merged in ASAP, as soon as I
> test it and make a download mirror for you. has an awesome
> new CDN setup, and once I implement, it
> will be easy to update tarballs and serve them to mass amounts of
> users.
> However, beyond that, we still need more done. First off, if you can
> help, we can help you! We can make lots of Windows build bots for
> people on demand, so if you're in desperate need of disk space or your
> computers are a bit slow, we can help accommodate.
> Right now, we have nightly builds with Gabor's[1] build system, and
> soon, we're working on a Phabricator integration, which should be
> great - and hopefully reduce the amount of breakage substantially.
> I also notice there is a ticket list of Windows issues[2], and that's
> fantastic. After a quick glance, a lot of these tickets are old,
> duplicates, or could possibly be closed or fixed easily. A good first
> task for any new contributor would be to go through this list, and try
> to replicate some of them! And you can always ask me - I can certainly
> help you navigate GHC a bit to get somewhere.
> But there are still other things. The Win32 package for example, is
> dreadfully lacking in maintainership. While we merge patches, it would
> be great to see a Windows developer spearhead and clean it up - we
> could even make some improvements in GHC itself based on this. This
> would be an excellent opportunity to make a good impact in the broader
> ecosystem!
> Finally, we desperately need someone to consult with when we're up a
> creek. Are certain patches OK for Windows? What's the best way to fix
> certain bugs, or implement certain features? I feel like often we try
> to think about this, but it's a bit lonely when nobody else is there
> to help! I'm not sure how to fix this, other than encouraging things
> like doing active code reviews and helping grind out some patches. But
> at the very minimum, I'd just like to talk with you about things
> perhaps!
> So in summary - the work so far is grand, and we want to help you do
> more! And I'm sure everyone can help - there's always so much to do
> and so little time, we need to encourage it all we can.
> As Simon says: Upward and Onward!
> [1]
> [2]
> --
> Regards,
> Austin Seipp, Haskell Consultant
> Well-Typed LLP,

Gintautas Miliauskas
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