Update on GHC 7.10 in Stackage

30 Apr 2015 Michael Snoyman

It seems that every time a blog post about Stackage comes out, someone comments on Reddit how excited they are for Stackage to be ready for GHC 7.10. Unfortunately, there's still an open issue about packages that have incorrect bounds or won't compile.

Well, as about 30 different package authors probably figured out today, I decided to take a crack at compiling Stackage with 7.10. This involved changing around some bounds, sending some pull requests, setting some expected test failures, and unfortunately temporarily removing a few packages from the build. But the result is well worth it: we now have a working build of Stackage with GHC 7.10!

To give some more information: this snapshot has 1028 packages, compared to 1106 for GHC 7.8. When updating the build-constraints.yaml file, I added the phrase "GHC 7.10" next to every modification I made. I encourage people to take a look at the file and see if there are any projects you'd like to send a pull request to and add GHC 7.10 support. If you do so, please ping me once the change is on Hackage so I can add it back to Stackage.

The question is: what do we do now? I'm interested in other opinions, but my recommendation is:

  • Early next week, I switch over the official nightly builds to start using GHC 7.10. LTS 2 will continue running, and will use GHC 7.8 as it does already. (LTS releases never change GHC major version.)
  • We work on improving the package and test coverage for GHC 7.10.
  • No earlier than July 1 do we release LTS 3, which will support GHC 7.10. If there is concern that the release isn't ready yet, we can hold off an extra month (though I doubt that will be necessary).

To ease the burden on package maintainers, LTS support cycles do not overlap. LTS 2 will be supported for a minimum of 3 months from its initial release (April 1, 2015), which is why LTS 3 will be released no sooner than July 1, 2015.

I'm quite surprised and excited that Stackage was able to move to GHC 7.10 so quickly. Thank you to package authors for updated your code so quickly!

comments powered by Disqus

Copyright © 2013-2017 FP Complete Corp. All rights reserved