GHC Weekly News - 2014/12/16

Austin Seipp austin at
Tue Dec 16 21:11:26 UTC 2014

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

  - Joachim Breitner has gotten the new GHC 7.8.4 package to
tentatively build on ARM quite easily for Debian. Austin also took the
liberty of merging all the needed patches; they'll be part of the
7.8.4 release

  - Greg Weber announced he's taken the time to set up a Docker image
for GHC development - if you're on Linux, Greg's image should help you
get up to speed with a GHC development environment in minutes!

  - Lennart Kolmodin has spent time working on autocompletion for GHC,
and 7.10 will ship with bash completion scripts - which package
maintainers and distributions can now ship for their users. Thank you

  - Adam Gundry has a question about the new type checker plugin
infrastructure; in particular - how do we deal with the serialization
of type checker evidence that plugins may want to create or pass
around on their own? Richard, Simon and Iavor weigh in.

  - 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.

  - David Spies has hit a very strange situation with GHC 7.8.3
running out of memory. But it turned out this was a change in 7.8, in
relation to how stacks were managed. Phew!

  - Austin made a final call for 7.8.4 bugfixes. He plans on making
the final release this week, if nobody has any other major complaints.

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.

  - Austin will be landing Phab:D169 and Phab:D396 soon to get it into
7.10.1 RC1.

  - 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.


Austin Seipp, Haskell Consultant
Well-Typed LLP,

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