Packages and modules

[Simon Marlow]

Malcolm Wallace wrote:
> Aaron Denney <wnoise at ofb.net> wrote:
> 
> 
>>>>Package names should never appear in source files IMHO.
>>>
>>>I tend to the opposite view.
>>
>>Then, as John points out, how is package Foo module A.B.C and package
>>Bar module A.B.C any different than modules Foo.A.B.C and Bar.A.B.C?
> 
> 
> I have great sympathy with this view - that packages are little
> different from a top-level name in the hierarchy.
> 
> But Simon PJ's comment (on the wiki page) about the difference between
> specifying the _purpose_ of a module in its name, and the _provenance_
> of a module in its package identifier, was very convincing.
> 
> I have added (yet another) alternative proposal, to the wiki here:
>     http://hackage.haskell.org/trac/ghc/wiki/GhcPackagesWithGrafting

I've digested this, and I hope can regurgitate the key points for anyone 
wishing to grasp it quickly.  Please correct me if I get anything wrong:

   - the proposal is to let you specify grafting in the source code

   - you graft a *sub-hierarchy* of a package anywhere in the
     global module namespace (the sub-hiearchy bit is new, I haven't
     seen this proposed before).

   - you can also graft a sub-hierarchy of a package onto the
     *current module*, so that it becomes available when importing
     this module.  This is new too.

Personally I'm not convinced the extra generality of grafting 
sub-hierarchies is necessary.  The re-export idea is interesting, though.

Cheers,
	Simon