RE: Plan for GHC 9.2

Simon Peyton Jones via ghc-devs writes:

Yes I agree, unlifted data types would be terrific.

From: ghc-devs On Behalf Of Sebastian Graf Sent: 11 February 2021 10:25 To: Ben Gamari Cc: ghc-devs Subject: Re: Plan for GHC 9.2

Hi,

Since my hopes of finally merging Nested CPR have recently been crushed again, I hope that we can include the implementation of the UnliftedDatatypes extension (proposalhttps://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fblob%2Fmaster%2Fproposals%2F0265-unlifted-datatypes.rst&data=04%7C01%7Csimonpj%40microsoft.com%7C730e3d94506e454a0e9808d8ce777010%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637486360556220696%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=RtIcZVbhIhqLo2KvXzUME5alwqQM7pI2e2dTLFGSGkI%3D&reserved=0, implementationhttps://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fmerge_requests%2F2218&data=04%7C01%7Csimonpj%40microsoft.com%7C730e3d94506e454a0e9808d8ce777010%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637486360556230694%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=71V9d0KIbAjVD5h9B6ZtmO%2FCDpFI3ZtcfOBt5%2BTUEeY%3D&reserved=0). It was on ice since it depends on the BoxedRep proposal, but if BoxedRep is going to make it, surely UnliftedDatatypes can make it, too.

I expect quite a few bugs, simply because I don't have much code to test it on yet. But I'm very confident that existing code isn't impacted by that, as most of the functionality (CodeGen for unlifted types, most importantly) was already there and I only had to refine a conditional here and there.

It would indeed be very exciting to finally have UnliftedDataTypes. If things turn out to be non-trivial then I think we should open to letting it slide for 9.4, but otherwise I am open to merging for 9.2 if a patch appeared. Cheers, - Ben