Re: Developer story: Foreign data types (example with HTML)

	If anything seems to question the below I am just attempting to get clarification.

> ** The Problem --------------------------------------------------------
> 
> Many languages allow to create new data types (classes, typedefs, etc)
> but they don't allow new semantics with them.

	This is the whole goal of the PCL macro system.  I need to just see if
we are talking about the same thing.

> For example, I can't say:
> 
>     HTML div = <Div class="demo">
> 	<b>
> 	    This is some text.
> 	</b>
>     </Div>;

So far I see no issue except for maybe interoperability with some non-OO paradigm but
I don't think this is an issue since the above is nothing but a meta-paradigm.

> or even improve on that syntax:
> 
>     HTML div = Div (
> 	class="demo",
> 	Bold ('Some text'),
>     )

	Either way should work just fine.

> ** Proposed Solution --------------------------------------------------
> 
> Pragmatic should allow to extend the compiler with new data types
> and new syntax with new semantics. In the end, I should be able to
> say things like this:
> 
>     HTMLFragment a = HTML (url="http://some.doma.in/path/to/document.html")//Div[@class == "demo"]

	I am sure we can make this even nicer syntatically in the long run.  My first
real app for Pragmatic is a blackboard (smart clipboard) GIS application that needs to target
the web as well as other front end viewers so there will be a rich HTML meta-paradigm in Pragmatic.

> The syntax extension should allow to change sematics without
> any additional keywords. For example, when I have an XML file
> which contain information about items in stock:
> 
>     <root>
> 	<item>
> 	    <name>CD-RW</name>
> 	    <count>5</count>
> 	<item>
>     </root>

	Weither or not a meta/first class paradigm pushs this beyond the PCL level is
upto it... I personally think one of the requirements for a first class paradigm to be
accepted as such will be to impliment paradigm extension without having to drop all the 
way to PCL macros.

> Then I want to be able to modify the count with this code:
> 
>     XML document = XML (url="stock.xml")
> 
>     // Does the item exist?
>     XMLFragment select = document//item/name/[text() == 'CD-RW'];
>     if select:
> 	// Find the count element of the selection,
> 	// convert it to int and decrement it
> 	select/../count -= 1
> 	
> 
>     // Rename "stock.xml" to "stock.xml.bak"
>     // and save the document as "stock.xml".
>     document.saveWithBackup ()

	If the XML meta-paradigm is implimented with first class paradigm standards intack
this should be trivial.

	--Aryeh

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