[Haskell-cafe] 6.12.1 planning

Simon Marlow marlowsd at gmail.com
Tue Jun 30 06:14:20 EDT 2009

Hi Folks,

As usual, we're planning a major release of GHC around September. 
Here's our list of the main items currently scheduled for 6.12.1, and 
their status.  If you have the time and inclination to help with any of 
these, please get involved!

* Parallel performance.  6.12.1 will ship with the improvements to 
parallel performance described in our ICFP 2009 paper.  Still to do: 
overhaul the +RTS GC settings, tune for good performance by default.

* Parallel profiling: the new RTS tracing features will be included, and 
we hope to have a release of ThreadScope to coincide with GHC 6.12.1. 
ThreadScope is written using gtk2hs, and could benefit from someone with 
expertise in producing polished gtk2hs apps - if you can lend a hand, 
contact Satnam Singh <satnams at microsoft.com>.

* Unicode I/O: the new Unicode I/O library is in, and will ship with 
6.12.1.  Still to do: decide on the public API for changing encodings 
and newline conversion.

* Shared libraries: we intend to ship with shared library support on at 
least x86/Linux and x86-64/Linux.  There are various tasks remaining to 
do here - Duncan, can we have a summary?

* Data Parallel Haskell.  Manuel, can you comment on the state of play? 
  What can we expect in time for 6.12.1?

* Plugin support in GHC.  The patches are not yet in GHC, and as far as 
I know are awaiting review - Simon, can you say more?

* The new backend code generator.  At the moment, it seems unlikely that 
GHC 6.12.1 will ship with the new code generator enabled by default, 
although it may well be available for testing.  Meanwhile, work on it 

The smaller items are all embodied in tickets, here are the tickets 
currently in the 6.12.1 milestone (135):


and on the 6.12 branch (251):


I estimate there are 2 man years of work here - needless to say, we 
aren't going to fix all these tickets :)  As usual, if you want to vote 
for something, add your email to the CC field of the ticket.

Several of these tickets would make good tasks for a fledgling GHC 
hacker.  e.g.  http://hackage.haskell.org/trac/ghc/ticket/2362 (allow 
full import syntax in GHCi) has a lot of support, and is a nice 
self-contained task (but not a small one).

Even if you're not a GHC hacker you can still help, e.g. by helping to 
narrow down the cause of a bug, or verifying a bug on your platform.

Let me remind people that GHC HEAD has the new build system, and it's 
actually rather pleasant to work with.  Even if you have no idea what 
you're doing, you can always say 'make' at the top level and the build 
system will figure out what needs doing (ok, so that's what build 
systems are supposed to do, but GHC's has never quite managed it until 


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