[clean-list] Comments on the module system

[Marco Kesseler]

>> >     One of the things that's (sorely, IMO) missing from the Clean module
>> >system is qualified names, where you refer to the identifiers in a module 
>> >using ModuleName.identifier or some equivalent syntax. 
>> >
>> >     Another issue that I've mentioned is the lack of hierarchy. Even
>> >rather pathetic (compared to Clean) languages like Java have hierarchical 
>> >namespaces and I think it's a good idea. 
>> 
>> In principle I agree that it is a good idea to have namespaces of 
>> some sort,
>> but I seriously doubt whether namespaces should be related to module 
>> names
>> and module hierarchy. This will lead to trouble when one starts 
>> rearanging modules.
>
>If you mean that hierarchical namespaces shouldn't map to filesystem 
>directory
>hierarchy, I agree. However, I think modules should define scopes. Think of 
>the ML module system without functors, or Ada packages without generics. 
>Mercury, which is a kind of cousin to Clean, is a good source of design
>ideas here (though I prefer separate interface and implementation modules 
>like Clean and Ada).

Modules already define scopes, in the public/private sense, but I 
would not couple this to namespaces.

I am not too familiar with the ML, Ada and Mercury solution. However, 
I think
that it would be useful to add definitions to a particular namespace 
without
having to add it to a particular module.

Consider for example the case that one wants to extend some 
'standard' namespace with new definitions. In such a case it is 
probably unwise to
touch the original implementation modules, even if one does have the
sources.

Furthermore, in a system of reasonable size, there will often be a lot
of modules, which makes it hard for a programmmer to find out in which
module a particular definition resides. A library of a particular party
will usually have no conflicting names. These could all be placed in a
single namespace, which is quite convenient, and easy to remember.

But maybe I am overlooking something?

regards,
Marco