Release plans

[Simon Marlow]

We'd like to solicit comments from the community on our plans for future GHC 
releases.  The current situation is this:

  - 6.6.1 is nearly ready to go (perhaps this week, please test the RC!)
  - 6.6.2 has ~35 outstanding tickets
  - 6.8 has ~150 outstanding tickets

the default option would be to work on 6.6.2 and release it in a couple of 
months, while continuing to work on 6.8 for a release in ~6 months or so.

However, there's another option: we could skip 6.6.2 and head straight for 6.8, 
the idea being to stabilise 6.8 with the existing feature set (plus a few 
important developments in progress), so that we can get these features out in a 
release sooner rather than later.  The 6.6.2 tickets would be moved to 6.8, and 
most of the outstanding 6.8 tickets would be pushed to 6.8.1 or later, retaining 
only the features/bug-fixes that are essential for the 6.8 release.

Here's a quick summary of the major developments that we already have in the 6.8 
codebase:

- Associated data types, and the new FC intermediate language
- GHCi debugger (although there's an overhaul of the breakpoint support almost
   ready to go in)
- Coverage (HPC)
- GADTs + typeclasses
- more packages moved from core to extralibs
- GHC API changes, compile to object code inside GHCi
- performance improvements: simplifier rewrite, and SpecConstr improvements
- standalone deriving declarations
- left-to-right impredicative instantiation: runST $ foo

Here are the features in progress that we'd like to get into 6.8:

- pointer-tagging (15% perf improvement for compiled code)
- get external core working again
- base package breakup (see discussion on libraries list)
- list fusion

We think the above feature set makes for a pretty strong 6.8 release.

What do you think of this plan?  Are there features/bug-fixes that you really 
want to see in 6.8?

Cheers,
	Simon & the GHC Team