benefits of extralibs/consequences of exceptions (Re: head aches in parser/Parser.hs)

[Simon Marlow]

Max Bolingbroke wrote:
>> Packages that explicitly depend on base-3.x will continue to work.
>> Unfortunately these are few and far between, despite our warnings after the
>> 6.8 release.
> 
> If this was reccomended practice, then I must have missed where it was
> documented. In particular, the "Upgrading packages to work with recent
> Cabal and GHC versions" link from haskell.org/cabal leads to
> http://haskell.org/haskellwiki/Upgrading_packages, which suggests:
> 
> """
> library
>   if flag(splitBase)
>     build-depends: base >= 3, containers
>   else
>     build-depends: base < 3
> """
> 
> Unless my understanding is wrong, this will consume base-4 while
> ignoring your new compatibility base-3.
> 
> Where should Haskellers be looking to find these reccomendations, if
> not on the official Cabal site?

http://www.haskell.org/haskellwiki/Package_versioning_policy

clearly we should do a better job of publicising this, though.  Also we 
plan to have Cabal emit warnings when the policy is not being followed.

Cheers,
	Simon