GHC 8.10.1 Release Plan

Matthew Pickering matthewtpickering at
Thu Sep 19 21:25:02 UTC 2019

I also really think we should fix 15455 before 8.10 is released.

It's a major space leak in the simplifier which has already been
present for 3 major versions now which affects a popular package.



On Wed, Sep 18, 2019 at 9:08 PM Ben Gamari <ben at> wrote:
> tl;dr. If you have unmerged work that you would like to be in GHC 8.10 please
>        reply to this email and submit it for review in the next couple
>        of weeks.
> Hello everyone,
> Now that GHC 8.8.1 is behind us it is time that we begin thinking about
> 8.10. There seems to be broad consensus within the subset of the
> community that I sampled that we should try to hold to the usual release
> date near the end of year for 8.10.1. I believe that this is a feasible
> goal with the caveat that we push the final release back by a couple of
> weeks in recognition that busy schedules of the holiday season tends to
> throw unexpected wrenches into the release process.
> In particular I would suggest the following concrete schedule:
>     October  18 2019:  start of one week freeze in preparation for branching
>     October  25 2019:  ghc-8.10 branch cut
>     November 8  2019:  8.10.1-alpha1
>     November 22 2019:  8.10.1-alpha2
>     December 6  2019:  8.10.1-alpha3
>     December 20 2019:  8.10.1-rc1
>     January  10 2020:  Final 8.10.1 release
> If you have yet-unmerged work that you would like to see in GHC 8.10
> please do be in touch and open a merge request ASAP.
> One obvious question is how we will avoid the many delays that plagued
> the 8.8.1 release. Without delving too deep into the specific reasons for
> these delays, the reasons fell into two buckets:
>  1. delays due to CI stabilization
>  2. coordination delays with upstream libraries
>  3. fallout from MonadFail changes which landed only late in the release
>     cycle
> Of these, (1) is largely behind us and (3) will be avoided by ensuring
> that core libraries changes are landed *before* the branch date.
> This leaves consideration (2). The problem of upstream library
> coordination has always been a tricky one but has grown more acute as
> our release schedule has accelerated. While no technical solution will
> eliminate the issue entirely, we believe that decoupling GHC's release
> schedule from those of its dependencies' is an important mitigation.
> We will be discussing this with upstream library maintainers in
> the coming weeks to establish how we can ensure that releases are
> available well ahead of the GHC 8.10 release, ideally by alpha2.
> Cheers,
> - Ben
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