The base library and GHC 6.10

[Simon Peyton-Jones]

| I'd really like to see the real issues addressed before we start
| worrying about names, as this has turned out to be a rats nest
| of bugs, including:

I'm all for addressing the real issues!  But there are two time-frames involved

a) In the next fortnight we must decide what stays in 'base' and what moves to the new 'syb' package.

b) On a longer timescale, the 'syb' package maintainers can improve the library.

The whole point of splitting syb out is to decouple (b) from (a).

I'm currently focused on (a), because it is urgent, and this is the discussion that Jose is now kindly chairing.  (b) remains important, but it is less urgent.


Concerning the GHC-related parts of Claus's specific  points:

| - ghc sessions retaining instances (#2182), leading to build errors
|     even in separate module hierarchies

Yes I agree this is bad, but I don't think I can fix it in time for 6.10; it's a consequence of an ill-made but fairly deeply wired in design choice.

| - ghc listing "orphan instances" as a performance issue,
|     re-emphasized recently by warnings turned into errors, which
|     has led some to believe they are a design fault, rather than a
|     representation of a valid design decision

They are not turned into errors.  They are simply warnings.  They only appear if you ask for them.  If you use -Werror then they turn into errors, but then you asked for that!  (The recent change is that previously they were second-class warnings that did not have this property.)

Simon