On Tue, Sep 02, 2008 at 09:46:09PM +0100, Claus Reinke wrote:
2 the "standard"/"dubious" separation of instances was entirely preliminary; following the recent discussion, I would suggest to split the instances into three groups, in three separate modules:
[standard]: fully implemented 'Data' instances (no runtime errors). one should probably reclassify 'Ratio a' in here.
[partial]: partially implemented instances (usually for abstract types, which 'Data' doesn't handle well; whether that can be mended without changing the class remains to be seen); these include 'Array a b', 'ThreadId', etc (previously in 'Standard') and the pointer types (previously in 'Dubious'); if these instances can be completed, existing clients will simply work better (fewer runtime crashes)
If the Data class, your [standard] instances (including Ratio and Complex) and the instances for FFI pointer types are in base, then the packages you listed (array, bytestring, containers, haskell-src, network, packedstring and template-haskell) need no longer depend on syb, and syb need no longer be a boot package. That would give maximal freedom to develop syb independently, wouldn't it? (Changes to Data can't be independent of GHC, and the instances of the types listed are canonical, aren't they?) This wouldn't allow you to hide the partial instances for the pointer types, but it would be hard to stop them leaking anyway, as they're used by several of the above packages.