GHC Weekly News - 2014/09/30

thoughtpolice - 2014-09-30

Hi *,

Here’s some news for y’all! Apologizes about the unavailability last week; the internet wasn’t exactly a very fun place for a system administrator…

So without delay, here’s the current recap of the past two weeks:

  • Lots of merged code and code reviews have gone in, and a lot of commits: in the past two weeks since the last update, ghc.git has seen just over 100 commits, from about a dozen different developers.

  • As part of those patches, a significant amount of them have gone towards implementing the “Burning Bridges Proposal” or BBP for the base library. This is a set of changes to base that have generalized many parts of the API, by putting Traversable and Foldable in the Prelude. This required a bit of shoveling by Herbert, but now this is all in GHC HEAD, and will be part of 7.10:

    • Prelude combinators, like mapM, have been generalized to the Traversable and Foldable classes.
    • Several other modules, like Control.Monad and Data.List, have been generalized to Traversable and Foldable where applicable.
    • Control.Monad combinators generalized to Applicative where possible.
    • Similarly, MonadPlus combinators like guard are generalized to Alternative.
    • Foldable has been extended with new methods, like length and null.

  • But also, GHC’s compiler is now tab-free! That’s right, after what seemed like a million years, a very large portion of the code has been detabbed, and -fwarn-tabs is now on by default in the GHC build.

  • There are an assortment of other changes: GHC’s linker is not as loud1, and various documentation improvements.

  • The windows build is broken again unfortunately, this time due to what seems to be a Cabal update, I think. Austin is once again on the case.

  • The HCAR draft for October has seen some nice improvements. If you’re a developer, please amend things. If you’re a user, read with eager anticipation of all the new features! 2

  • It turns out the new Applicative/Monad changes have unfortunately broken the haskell98 and haskell2010 packages, with an unclear migration strategy for the future: see #9590. For GHC 7.10, it seems the haskell2010 packages will need to change to accomodate these standard deviations. If any users of the haskell98 or haskell2010 packages would speak up to help, that would be fantastic. The discussion will surely continue for a little bit - 7.10 is still a ways off.

In miscellaneous news:

  • ghc.haskell.org may have been temporarily unavailable during this weekend due to an emergency downtime with our provider for a security update, but the window was quite small.

  • Relatedly (but not the exact same scenario), the internet also caught fire in several other places, requiring quite a lot of careful watching and remediation after the Bash “ShellShock” bug hit last week.

And I think that sums it up quite nicely, folks!

Closed tickets for the past two weeks include (there are a lot of them!): #9650, #7068, #5190, #5880, #8374, #9603, #3303, #3470, #3509, #781, #8115, #9641, #9191, #9515, #9326, #7987, #9634, #9576, #9612, #9635, #8593, #7544, #8529, #9338, #5794, #9535, #3646, #617, #8026, #8480, #8881, #9366, #8251, #7673, #8983, #8369, #8897, #8070, #9550, #9057, #9629, #8836, #8960, #8941, #9565, #9589, #5248, #8918, #9568, #9620, #1042, #9557, #7863, #5647, #9610, #5395, #9580, #9529, #4426, #9607, #9592, #8097, #9559, #9560, #4218, #9602, #9528, #9530, #9423, #9400, #1407, #9598, #9597.

I’d like to mention that for the above tickets, a huge amount of them were closed by one of our newest contributors, Thomas Miedema, who went through the bug tracker and confirmed or closed a large majority of them. I lost track of how many. Thanks Thomas!