On 09 March 2005 08:46, Simon Peyton-Jones wrote:
That wasn't what I intended (though it would be possible) At present module M( module A ) where ... does not cause qualified names in the importing scope: import M as T -- introduces only f, g, T.f, T.g Simply using "as" on the export clause would not change that, would it? In fact, as John M says, it'd be a non-op.
In short, my suggestion is that using "qualified" in an export list is the *only* way to introduce extra module qualifiers in an importing scope. Using "as" in an export item would serve only to change what the qualifier is, and is therefore irrelevant if you don't have "qualified".
Yes. I'd like to question whether specifying the entities in a qualified module export is really necessary. Most examples can be rewritten using restricted imports instead, eg.: module A ( qualified module B (f,g) ) where import B rewrites as: module A ( qualfied module B' as B ) where import B (f,g) as B' import B and I'm sure you can see how to rewrite the others. Sure, the first version is more readable, but I question whether we need the extra generality. It's extra rules in the syntax and extra work that the implementation has to do. The exception (as Simon already pointed out to me) is when you're exporting entities defined by the current module, with a qualifier. You can't rewrite that unless the implementation supports self-imports, which I believe is tricky to implement (GHC doesn't support it). Cheers, Simon