GHC 8.0 feature freeze imminent

Simon Peyton Jones simonpj at
Thu Dec 17 10:59:54 UTC 2015


I’m afraid not.   The underlying technology is there, since this week.  But we need to think carefully about the transition (since it’s a big library change), and I simply have not had time to do that.  Moreover not everything about the new library design is settled.

So we decided to get 8.0 out and then work with the community on exactly what the new API should be.  I’m actually delighted that you are still engaged with this (haven’t heard much from you for a while), and I’d like to start on it in the new year.

Would you be prepared to be an active participant?  Or even be the lead player?  I’ve written a paper that I’ll put up shortly that goes through the idea of type-indexed type representations in some detail.



From: ghc-devs [mailto:ghc-devs-bounces at] On Behalf Of Boespflug, Mathieu
Sent: 17 December 2015 10:23
To: Ben Gamari <ben at>
Cc: GHC developers <ghc-devs at>
Subject: Re: GHC 8.0 feature freeze imminent

Hi Ben,

does GHC HEAD include the cleanup to the Typeable story detailed here, My understanding was that this blocked on kind equalities, which was merged just recently. See this quote from that page:

> Step 3 (allowing TypeRep to be fully decomposed in a type safe way) absolutely requires kind equalities.

Making static pointers safe in GHC 8.0 is dependent on a solution to this particular issue.

Mathieu Boespflug
Founder at<>.

On 14 December 2015 at 14:38, Ben Gamari <ben at<mailto:ben at>> wrote:
Hello GHCers,

Last Friday Richard Eisenberg's long-awaited no-kinds branch landed in
`master`. Being one of the defining features of the 8.0 release, we bent
the feature freeze schedule (initially slated for sometime last week) a
bit to accomodate this piece of work.

Now that Richard's work is in, we will set the official freeze date for
Monday December 21st so that there is time to review and merge some
queued work which we've been queuing for after the no-kinds merge. If
you have work still outstanding then you should talk to either me or
Austin ASAP if you have not done so already. We will be discussing the
release schedule for 8.0 during the GHC today.


- Ben

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