I have always considered the LLVM code generator my responsibility and will continue to do so. I don't seem to find the time to make improvements to it but make sure to keep it bug free and working with the latest LLVM releases. So if others want are interested in working on it then there is plenty of room for that but I'll continue to maintain it and be responsible for it at the least. On 5 December 2012 08:56, Simon Peyton-Jones wrote:

Friends

You'll have seen Simon Marlow's recent announcement (included below):

| Today I'm announcing that I'm leaving Microsoft Research.

Simon Marlow and I have worked together on GHC for nearly two decades. During much of that time we have shared a cup of coffee every morning (one cup each, since you ask), to discuss what's going on in GHC-land. We had frequent detailed and illuminating debates about design alternatives. Simon is the absolute master of GHC's code generation, runtime system, garbage collector, support for parallel execution, and much else besides. His sheer programming skill in rooting out obscure and hard-to-reproduce runtime system bugs has always amazed me. He is more than just a great hacker, of course. He is a leader in our community, has a strong publication record, chaired the Haskell Prime committee for a year, and is sought after for tutorials about parallel programming.

I owe Simon a great debt, as I think we all do, for the care and skill he has lavished on GHC. He's not going to disappear entirely, but he will be spending much less time on GHC than in the past. That is a change, but it's a change that was always going to happen sometime, and while change is sometimes uncomfortable, it can also open up new possibilities.

GHC is over 20, and like my own children (who are actually all a bit younger than GHC), that's not a bad time to start to head out into the world. Over time, more and more people have started to help with the task of developing and maintaining GHC. We'll have to do more of that. These days GHC has a very large "surface area" (running on different platforms, dynamic linking, debugger, profiler, GHCi, libraries and Cabal, etc etc), and has grown far beyond what any single person or research group can manage.

Lest you should wonder, I myself will certainly continue to work on GHC. But my job is to be a *researcher*, and I am not well equipped -- in temperament or expertise -- to deal with the myriad complexities of deployment, upgrade policy, portability, and the like. Well Typed (mostly in the guise of Ian Lynagh) will continue to handle some of these issues, but again there is too much for one person to do.

So we need your help. Seriously. Rather than just thinking "GHC HQ will sort it out", I would welcome you saying "Shall I take responsibility for X?". Johan, Bryan, and others offering to be GHC Performance Tsars is a great recent example. But don't wait to be asked: just make an offer if you see a gap or an open ticket --- and I think there will be plenty of those. Particularly valuable are offers to take responsibility for a particular area (eg the LLVM code generator, or the FFI). I'm hoping that this sea change will prove to be quite empowering, with GHC becoming more and more a community project, more resilient with fewer single points of failure.

I am going to miss that cup of coffee though. Thank you Simon! Facebook is lucky to have you.

Onward and upward.

Simon (PJ)

| -----Original Message----- | From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell- | users-bounces@haskell.org] On Behalf Of Simon Marlow | Sent: 22 November 2012 11:27 | To: haskell; glasgow-haskell-users@haskell.org | Subject: Leaving Microsoft | | Today I'm announcing that I'm leaving Microsoft Research. | | My plan is to take a break to finish the book on Parallel and Concurrent | Haskell for O'Reilly, before taking up a position at Facebook in the UK | in March 2013. | | This is undoubtedly a big change, both for me and for the Haskell | community. I'll be stepping back from full-time GHC development and | research and heading into industry, hopefully to use Haskell. It's an | incredibly exciting opportunity for me, and one that I hope will | ultimately be a good thing for Haskell too. | | What does this mean for GHC? Obviously I'll have much less time to work | on GHC, but I do hope to find time to fix a few bugs and keep things | working smoothly. Simon Peyton Jones will still be leading the project, | and we'll still have support from Ian Lynagh, and of course the | community of regular contributors. Things are in a reasonably stable | state - there haven't been any major architectural changes in the RTS | lately, and while we have just completed the switchover to the new code | generator, I've been working over the past few weeks to squeeze out all | the bugs I can find, and I'll continue to do that over the coming months | up to the 7.8.1 release. | | In due course I hope that GHC can attract more of you talented hackers | to climb the learning curve and start working on the internals, in | particular the runtime and code generators, and I'll do my best to help | that happen. | | Cheers, | Simon

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On 06/12/2012, at 3:56 , Simon Peyton-Jones wrote:

Particularly valuable are offers to take responsibility for a particular area (eg the LLVM code generator, or the FFI). I'm hoping that this sea change will prove to be quite empowering, with GHC becoming more and more a community project, more resilient with fewer single points of failure.

The LLVM project has recently come to the same point. The codebase has become too large for Chris Lattner to keep track of it all, so they've moved to a formal "Code Ownership" model. People own particular directories of the code base, and the code owners are expected to review patches for those directories. The GHC project doesn't have a formal patch review process, I think because the people with commit access on d.h.o generally know who owns what. Up until last week I think it was "SPJ owns the type checker and simplifier, and SM owns everything else." :-) At this stage, I think it would help if we followed the LLVM approach of having a formal CODE_OWNERS file in the root path of the repo explicitly listing the code owners. That way GHC HQ knows what's covered and what still needs a maintainer. The LLVM version is here [1]. Code owners would: 1) Be the go-to person when other developers have questions about that code. 2) Fix bugs in it that no-one else has claimed. 3) Generally keep the code tidy, documented and well-maintained. Simon: do you want a CODE_OWNERS file? If so then I can start it. I think it's better to have it directly in the repo than on the wiki, that way no-one that works on the code can miss it. I suppose I'm the default owner of the register allocators and non-LLVM native code generators. Ben. [1] http://llvm.org/viewvc/llvm-project/llvm/trunk/CODE_OWNERS.TXT?view=markup