cabal release (was: cabal experiences)

[Simon Marlow]

On 12 December 2005 15:31, Ian Lynagh wrote:

> On Mon, Dec 12, 2005 at 03:14:09PM +0000, Duncan Coutts wrote:
>> 
>> In Gentoo we made a decision to ship Cabal-1.1.3 with GHC 6.4.1.
>> That is after installing GHC 6.4.1 we unregister Cabal-1.0 and
>> install Cabal-1.1.3.
> 
> If all distributions and users are going to have to do this to get a
> usable system[1] then it seems obvious to me that ghc should already
> come this way. That it doesn't causes headaches for packagers IME.

I tend to agree.  I'm not against breaking the rules in this case, since
shipping Cabal-1.0 in 6.4.2 would be distinctly sub-optimal.  Shipping
two versions of Cabal is possible, but the build system isn't really set
up to do this, so it's non-trivial work, and it still requires the user
to say 'ghc-pkg expose Cabal-1.1.4; ghc-pkg hide Cabal-1.0'.

Cabal is something of a special case, because its use is pretty much
restricted to Setup.lhs scripts, which can be considered part of the
build system rather than the code of a library or application.  So this
is build system API breakage, not library API breakage, m'lud ;-)

I'd be rather happier if we could solve the versioning issue with Cabal,
so that upgrading Cabal in the future doesn't automatically break code.
It might not be possible to do this the first time around, but now is
the time to design our way out of future problems.

Cheers,
	Simon