[Haskell] Re: Trying to install binary-0.4
simonmarhaskell at gmail.com
Mon Oct 29 06:52:09 EDT 2007
Thomas Schilling wrote:
> On Sun, 2007-10-28 at 13:49 -0400, Isaac Dupree wrote:
>> Simon Marlow wrote:
>>> Probably it could be made clearer. In 4.2 the idea is that instead of
>>> base-2.0 ==> base-3.0 + directory-1.0 + array-1.0 + ...
>>> you would replace
>>> base-2.0 ==> newbase-1.0 + directory-1.0 + array-1.0 + ...
>>> and additionally have a package base-3.0 that re-exports the whole of
>>> (newbase + directory + array + ...).
>> "Macros" in cabal: Why not just say that depending on base-3.0 actually
>> means that you have to depend on newbase-1.0, and directory-1.0, etc...
>> Why is compiler support needed? is it really possible that I still
>> don't understand?
> You'd still have the problem that every package has to specify this
> "macro" for itself. You'd want some global macro-database to avoid
> this. The better solution would be to just have a package that
> re-exports everything. I.e., the definition of package base-2.0 would
> look something like this:
> if has system has base-3.0, directory, array ...
> exposed-modules: Data.Maybe, Data.List, ...
And this runs into trouble when base-3.0 has changes to datatypes and/or
classes relative to base-2.0 (see 4.1 of
approach doesn't scale; it may be useful for providing backwards-compatible
versions of smaller packages, but impractical for base.
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