GHC Weekly News - 2015/01/07

thoughtpolice - 2015-01-07

Hi *,

it’s time for another GHC Weekly News! This week’s edition will actually be covering the last two/three weeks; your editor has missed the past few editions due to Holiday madness (and also some relaxation, which is not madness). It’s also our first news posting in 2015!

So let’s get going without any further delay!

GHC HQ met this week after the Christmas break; some of our notes include:

• Austin Seipp announced the GHC 7.8.4 release on behalf of the GHC development team. https://www.haskell.org/pipermail/haskell/2014-December/024395.html

• Austin Seipp also announced the GHC 7.10.1 RC on behalf of the GHC team, as well. https://www.haskell.org/pipermail/ghc-devs/2014-December/007781.html

• Since Austin is back, he’ll be spending some time finishing up all the remaining binary distributions for GHC 7.8.4 and GHC 7.10.1 RC1 (mostly, FreeBSD and OS X builds).

• We’ve found that 7.10.1 RC1 is working surprisingly well for users so far; to help users accommodate the changes, Herbert has conveniently written a migration guide for users for their most common problems when upgrading to 7.10.1: https://ghc.haskell.org/trac/ghc/wiki/Migration/7.10

• We’re aiming to release the 2nd Release Candidate for GHC 7.10.1 on January 19th. We’re hoping this will be the last RC, with 7.10.1 final popping up in the middle of February.

• GHC HQ may tentatively be working to release another GHC 7.8 release, but only for a specific purpose: to allow it to compile with 7.10.1. This will make it significantly easier for users to compile old GHCs (perhaps on newer platforms). However, we’re not yet 100% decided on this, and we will likely only do a ‘very minor release’ of the source tarball, should this be the case. Thanks to Edward Yang for helping with this.

• For future GHC releases on Windows, we’re looking into adopting Neil Mitchell’s new binary distribution of GHC, which is a nice installer that includes Cabal, MSYS and GHC. This should significantly lower the burden for Windows users to use GHC and update, ship or create packages. While we’re not 100% sure we’ll be able to have it ready for 7.10.1, it looks promising. Thanks Neil! (For more info, read Neil’s blog post here: http://neilmitchell.blogspot.co.at/2014/12/beta-testing-windows-minimal-ghc.html )

There’s also been some movement and chatter on the mailing lists, as usual.

• GHC 7.10 is coming close to a final release, planned in February; to help keep track of everything, users and developers are suggested to look at the GHC 7.10.1 status page as a source of truth from GHC HQ: https://ghc.haskell.org/trac/ghc/wiki/Status/GHC-7.10.1

• Jan Stolark is currently working on injective type families for GHC, but ran into a snag with Template Haskell while trying to understand GHC’s DsMeta module. Richard chimed in to help: https://www.haskell.org/pipermail/ghc-devs/2014-December/007719.html

• Austin Seipp opened a fun vote: what naming convention should we use for GHC buildbots? After posting the vote before the holidays, the results are in: GHC’s buildbots will take their names from famous logicians and computer scientists: https://www.haskell.org/pipermail/ghc-devs/2014-December/007723.html

• Carter Schonwald asked a simple question: are pattern synonyms usable in GHCi? The answer is ‘no’, but it seems Gergo is on the case to remedy that soon enough: https://www.haskell.org/pipermail/ghc-devs/2014-December/007724.html

• Anton Dessiatov has a question about GHC’s heap profiler information, but unfortunately his question has lingered. Can any GHC/Haskell hackers out there help him out? https://www.haskell.org/pipermail/ghc-devs/2014-December/007748.html

• Joachim Breitner made an exciting announcement: he’s working on a new performance dashboard for GHC, so we can more easily track and look at performance results over time. The current prototype looks great, and Joachim and Austin are working together to make this an official piece of GHC’s infrastructure: https://www.haskell.org/pipermail/ghc-devs/2015-January/007885.html

• Over the holiday, Simon went and implemented a nice new feature for GHC: detection of redundant constraints. This means if you mention Ord in a type signature, but actually use nothing which requires that constraint, GHC can properly warn about it. This will be going into 7.12: https://www.haskell.org/pipermail/ghc-devs/2015-January/007892.html

• Now that GHC 7.10 will feature support for DWARF based debugging information, Johan Tibell opened a very obvious discussion thread: what should we do about shipping GHC and its libraries with debug support? Peter chimed in with some notes - hopefully this will all be sorted out in time for 7.10.1 proper: https://www.haskell.org/pipermail/ghc-devs/2015-January/007851.html

Closed tickets the past few weeks include: #8984, #9880, #9732, #9783, #9575, #9860, #9316, #9845, #9913, #9909, #8650, #9881, #9919, #9732, #9783, #9915, #9914, #9751, #9744, #9879, #9876, #9032, #7473, #9764, #9067, #9852, #9847, #9891, #8909, #9954, #9508, #9586, and #9939.