Cabal vs Haskell [sic]

[Shae Matijs Erisson]

"S. Alexander Jacobson" <alex at alexjacobson.com> writes:

> 4. A set of modules may be dependent on a set of packages if and only if that
> set of packages is the only set of packages that may contain them.

I don't understand. What does this mean?
Modules must be contained by a package to depend on that package?

> 5. Since more than one set of packages may contain the same set of modules,
> the current Haskell story cannot be consistent with the current Cabal story.

Why can't multiple packages have the same set of modules?
-- 
Programming is the Magic Executable Fridge Poetry, | www.ScannedInAvian.com
It is machines made of thought, fueled by ideas.   | -- Shae Matijs Erisson