GHC on Windows (extended/broad discussion)

Austin Seipp austin at
Thu Oct 30 20:38:47 UTC 2014

Hey Gintautas,

Yes, I apologize about that (and I missed this request in my quick
read over this email yesterday). To be clear, I apologize if my
review/merge latencies are too long. :) What normally happens it that
I review and merge patches in bulk, about once or twice a week. I'll
review about, say, a dozen patches one day, and wait a few days for
more to come in, then sweep up everything in that time at once.

So there are two things: a review latency, *and* a merge latency.

However, two things are also clear:

 1) This is annoying for people who submit 'rapid improvements', e.g.
in the process of working on GHC, you may fix 4 or 5 things, and then
not having those in the mainline is a bit of a drain!
 2) Phabricator building patches actually means the merge latency can
be *shorter*, because in the past, we'd always have to double check if
a patch worked in the first place (so it took *even longer* before!)

Another thing is that I'm the primary person who lands things off
Phabricator, although occasionally other people do too. This is
somewhat suboptimal in some cases, since really, providing something
has the OK (from me or someone else), anyone should be able to merge
it. So I think this can be improved too.

Finally, it's also worth mentioning that Phabricator reviews are
special (and unlike GitHub) in that people who are *not* reviewers *do
not* see the patch by default! That means if I am the *only* person on
the review, it is pretty high guarantee that the review will only be
done by me, and it will only be merged by me, unless I poke someone
else. Others can see your review using a slightly different search
criterion, however, but that's not the default.

Note this is not a mistake - it is intentional in the design. Why?
Because realistically, I'd say for about 85% of the patches that come
in, they are irrelevant to 90% of all GHC developers, and
historically, 90% of developers will never bother committing it
either. It is often pointless to spam them with emails, and enlarging
their review queue beyond what's necessary makes things even *worse*
for them, since they can't tell what may really deserve their
attention. I do want more people reviewing code actively - but to do
that, there must be a tradeoff - we should try and keep contributor
burden low. Most developers are just our friends after all, including
you - not paid GHC hackers! I don't want to overburden you; we need

I am one of the exceptions to this: I realistically care and want to
see about 95% of all patches that go into the tree, at least to keep
up to date with what's happening, and also to ensure things get proper
oversight - by, say, adding someone else to a review who I want to
look at it. This is why I'm the common denominator, and a reviewer of
almost every patch (and I think I'm fairly keen on who might care
about what).

However it's clear that if this is slowing you down we should try to
fix it - we want you to help after all! We already have nearly 40
people with commit rights to GHC, and you've clearly dedicated
yourself to helping. That's fantastic. Perhaps it's time for you to
enter the fray as well so I can get out of your way. :) But I do still
want you to submit code reviews, as everyone else does - it really
does help everyone, and increases a sense of shared ownership, IMO.

In light of this though, I do think I need to ramp up my merge
frequency. So how does a plan of just trying to merge all outstanding
patches every day sound? This is normally very trivial amounts of time
these days, considering Phabricator tends to catch the most obvious

BTW: I merged your pull request on the Win32 repository, so we can
update MinGW - I didn't realize that it was open at all, and in fact I
completely forgot I had permissions to merge things on that
repository! Most of the external library management is normally dealt
with by Herbert or individual maintainers.

On Wed, Oct 29, 2014 at 6:36 AM, Gintautas Miliauskas
<gintautas at> wrote:
> By the way, regarding that repository, could someone merge my pull request?
> In general, it's a bit frustrating how a lot of the patches in the
> Phabricator queue seem to take a while to get noticed. Don't take it
> personally, I'm just sharing my impressions, but I do feel it's taking away
> some momentum - not good for me & other contributors, and not good for the
> project. I know reviewers are understaffed, maybe consider spreading commit
> rights a bit more widely until the situation improves?
> On Wed, Oct 29, 2014 at 11:04 AM, Herbert Valerio Riedel
> <hvriedel at> wrote:
>> On 2014-10-29 at 10:59:18 +0100, Phyx wrote:
>> [...]
>> >> 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
>> >
>> > A while back I was looking at adding some functionality to this
>> > package, but could never figure out which one was actually being
>> > used. I think there are multiple repositories out there.
>> I'm not sure which multiple repositories you have seen, but
>> points quite clearly to
>> and that's the official upstream repository GHC tracks (via a locally
>> mirrored repo at
>> Cheers,
>>   hvr
> --
> Gintautas Miliauskas
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at


Austin Seipp, Haskell Consultant
Well-Typed LLP,

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