GHC 7.8.1 RC2

Austin Seipp – Monday, 03 March 2014

all community ghc  

Today, GHC 7.8.1 RC2 has been released.

We've closed approximately 45 issues people filed against RC1. Thanks to everyone who has helped out!

There are actually quite a few nice improvements since then, and some stuff we'd like to announce.

iOS cross compiler binaries

This release features iOS cross compiler binaries, courtesy of Luke Iannini. You can download either ghc- or ghc- for the iOS ARM compiler or iOS Simulator, respectively.

To properly use the binary distribution, be sure to carefully read the README! Hopefully this process can be made less tedious in the future.

LZMA support for binary distributions

In my experience, lots of people use the binary distributions of GHC for their provided platform (to set up test environments, or because the version for their OS is out of date), and a smaller download for users always helps.

We're now offering LZMA (.tar.xz) compressed binary distributions. On average, these are half the size of their bzip2 counterparts – in some cases even more. The iOS ARM build, for example, is 125M for LZMA vs 267M for bzip2 – a ratio of greater than 50%.

One question now is: with these savings, should we keep supporting .tar.bzip2 distributions? GHC bindists are rather large – xz offers a lot of savings, and is available for every major platform, although it's not typically standard like bzip. But perhaps it's not too much of a burden. Please let us know what you think!

(In the future, this will also save considerable space with nightly build infrastructure as well!)

New PPC64 machine

GHC HQ now has a shiny, modern 64-bit POWER7 machine available, courtesy of Gustavo Luiz Duarte. Gustavo is a Fedora PPC64 maintainer, and approached me earlier this year and said he could give us access to a build machine. And now we've got a really nice one! And 7.8.1 works well on it, including dynamic GHCi and shared libraries.

This box is running Fedora 20, has 8 hardware threads split across two cores (one per socket) in a NUMA configuration, and a nice amount of RAM.

Many thanks to Gustavo for letting us use this – and also to OSUOSL, who is hosting it in their data center for us! Hopefully we'll be able to keep supporting this platform (we get a surprising amount of PPC/PPC64 related tickets!)

i386/amd64 Ubuntu PPA

Earlier this year, Herbert Valerio Riedel took the time to set up Ubuntu PPAs for Travis-CI, making it easy to test your Haskell packages using multiple GHC versions – from GHC 6.12 to 7.8 and HEAD.

This PPA repository now contains 7.8.1 RC2 binaries, available for download for both i386 and amd64 on Ubuntu 12.04 Precise. You should immediately be able to take advantage of these builds in your .travis.yml to test your packages. Furthermore, the binaries are separated from other versions and can coexist with existing packages.

To get started, add the PPA and install the 7.8.1 build:

$ sudo add-apt-repository -y ppa:hvr/ghc
$ sudo apt-get update
$ sudo apt-get install ghc-7.8.1
$ export PATH=/opt/ghc/7.8.1/bin:$PATH
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version

This PPA is also integrated into Herbert's multi-ghc-travis project that I mentioned earlier. Just follow the instructions in the, and be sure to enable:


inside your .travis.yml. You'll then automatically get build reports with RC2, and any future updates we push to the PPA (including the final version of 7.8.1).

For example, lens now builds with GHC 7.8.1!

Hopefully we can provide builds for all supported Ubuntu configurations in the future – not just Precise. for your Debian needs

Thanks to Joachim Breitner, our resident Debian Developer, we now have GHC HEAD builds available as Debian packages!

Currently there aren't 7.8.1 builds yet I'm afraid – but there will be a final version of 7.8.1 available upon release. In the mean time, feel free to use these repositories to test out the latest GHC if you're daring, and report issues to us!

And this leads me to...

Rackspace support

Earlier this year, I contacted Rackspace about one of their developer programs. Rackspace is a huge supporter of open source and has some great initiatives to help open source projects. I asked if they could help GHC – we wanted build machines.

Rackspace was extremely kind, and with the help of Jesse Noller, they've provided GHC with a few thousand USD per month in services! This was extremely nice of them, and really blew me away.

Rackspace is what powers – and not only that. GHC HQ now has machines available solely for testing/build purposes, including many new Windows and Linux instances.

In addition to that, we're using them for too – including a FreeBSD backup server (to be revamped soon), and the creation of our new Nagios monitoring infrastructure at

Right now, we've still got budget available to run more services. This venture is a bit of a joint one between GHC HQ and the current administrators, as we're using it for both of our needs at the moment.

What's next

We're hoping RC2 will be the final RC, and 7.8.1 proper will follow soon. In the mean time, please download the RC and file bugs if anything goes wrong!