GHC Weekly News - 2015/04/14

Austin Seipp austin at
Tue Apr 14 17:47:30 UTC 2015

(You can find a copy of this post online at

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 `ghc-devs at` is also a sure-fire way to get our

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 ==

  - Austin Seipp announced GHC

  - Mark Lentczner announced an alpha Haskell Platform

  - David Macek announced MSYS2 packages for GHC on Windows, and also
    asked for some help with continuous windows building - Windows
    hackers should help out!

  - Jan Stolarek reports about increased memory usage with GHC 7.10.1.

  - Thomas Miedema chimed into a thread started by Karel Gardas about
    better parallelizing the GHC build - and hopefully we can get
    something good out of

  - Austin Seipp made a call for help on working on and improving the
    GHC homepage, and luckily Sergey Bushnyak answered the call and
    has helped out!

  - Ozgun Ataman kicked off a thread about slower compilation times,
    with some nasty numbers. It's becoming more clear compiler
    performance should be a priority for 7.12, and we've let some
    things slip away from us:

  - 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

  - 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!

  - Simon Peyton Jones started a discussion about
    `GeneralizedNewtypeDeriving` and Safe Haskell, in particular,
    whatever the current status, our documentation doesn't accurately
    reflect it! Perhaps someone could help out writing the
    documentation based on the current status quo?

  - 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.

  - Alan Zimmerman has posted several questions and threads about the
    parser and the status of API annotations, which he's been
    furiously working on now that GHC 7.10 is being used on
    Hackage. Interested onlookers could learn a thing or two!

  - Gabor Greif has a question about some seemingly strange behavior
    regarding the interaction between poly-kinded `data` types and
    overlapping instances. Richard sez: this behavior is

== Noteworthy commits ==

  - Commit de1160be047790afde4ec76de0a81ba3be0c73fa - refactor the
    story around switch cases (with a code-size improvement)

  - Commit 995e8c1c8692b60c907c7d2ccea179d52ca8e69e - drop old
    `integer-gmp-0.5` source code.

  - Commit 59f7a7b6091e9c0564f3f370d09398d8c9cd8ad5 - Restore unwind
    information generation (fixes DWARF generation)

  - Commit 9f0f99fd41ff82cc223d3b682703e508efb564d2 - Fix an old bug
    in the demand analyzer (with some nice compiler performance

  - Commit a7524eaed33324e2155c47d4a705bef1d70a2b5b - Support for
    multiple signature files in scope (Backpack).

== 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.


Austin Seipp, Haskell Consultant
Well-Typed LLP,

More information about the ghc-devs mailing list