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. https://mail.haskell.org/pipermail/ghc-devs/2015-April/008862.html
  • 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. https://mail.haskell.org/pipermail/ghc-devs/2015-April/008902.html
  • 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. https://mail.haskell.org/pipermail/ghc-devs/2015-May/008904.html
  • 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! https://mail.haskell.org/pipermail/ghc-devs/2015-May/008992.html

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.

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