[Grace-core] Fwd: Some notes on pattern matching on the wiki

[Andrew P. Black]

On 5 Jul 2011, at 19:00 , Kim Bruce wrote:

>> 
>> 
>>> So what is the graceful view of nested classes anyway?
>> 
>> not sure yet. I think we are close to committing to something close to gBeta/Newspeak/ (Ceylon?) view 
>> but haven't hurtled over that waterfall quite yet..
>> 
>> that is - yep classes nest, modules are nested classes, class family inheritance (overriding inner classes in subclases) works right...
> 
> NO! NO! NO!  Modules are not nested classes!!!  They have nothing to do with each other!!!!  Modules are modules -- they are not used for generating new objects and are not extended using inheritance.  Why confuse the two very different concepts????
> 
> I wish you hadn't posted that without discussing it first ...

We clearly need to discuss this further.  But I don't see them as very different concepts.  They are both stylized uses of objects. But I think that it depends rather on what you want modules to do.

What /I/ want a module m to do is package up:

	a collection of new objects
	a collection of new factories (which are, of course, just a special cases of the above), and
	a collection of new types (which may also be a special cases of the above!)
	
These will need to be named in a way that separates them from other stuff that I may have named: m.obj and m.fact provide a great way to do this.   They will also need to be dependent on other modules, which are given to m as arguments.  (So, for example, m.Dictionary might depend on an argument to m that is a Set.)

Others may have different desiderata for modules.  I think that we will reach closure on this faster if we first talk about what they are /for/.  If our purposes can't be accomplished with objects, then we should certainly invent something else.  Otherwise: concepts "should not be multiplied beyond necessity"!

	Andrew