Cabal compatibility redeux

Robert Dockins robdockins at
Mon Jan 9 19:04:39 EST 2006

I'd just like to reseruct the conversation from here 
( for a 
quick moment if I might.  At the time I wrote:

>>>> This would greatly simplify the Distribution.Simple.UserHooks
>>>> structure bringing it from 34 fields to 14 fields, or so.
>>>> Downsides: Making pre and post hooks would now be slightly harder, and
>>>> it would break existing hooks-using code.
>>> I just want to mention that these kind of changes represent represent a
>>> VERY big problem. I discussed that issue at some length in an email I
>>> intended to send to this list very recently, but it seems to have gotten
>>> lost.
>> Are you sure they represent a very big problem in practice and not
>> just in theory?  
> [snip]
> Well, obviously it isn't a practical problem yet.  If it was we'd have
> people screaming about it on the lists.

I would now like to add to the theoretical arguments I made then the evidence 
that the HSQL driver package for MySQL uses the user hooks of Cabal and I 
have just experienced a case of Cabal version skew breaking a build system, 
because this package will not build for me using Cabal 1.1.3.  I am unsure at 
the moment if this is because my Cabal is too new or too old, and I now face 
the prospect of 1) hacking on the build system to match my cabal, 2) trying 
random cabal upgrades/downgrades or 3) pinging the package maintainers to 
figure out how to build this package.

Rob Dockins

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