Re: The IDS, the EDS and the DBMS

From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Fri, 10 Sep 2004 22:55:55 +0200
Message-ID: <414214df$0$568$e4fe514c_at_news.xs4all.nl>

Marshall Spight wrote:

> erk wrote:

>>Type implementation; I think Date had it right in suggesting that type
>>implementations could be done in a variety of languages, and even that
>>those languages might be different than those used in the rest of the
>>app...

>
> I don't see any value to Date's position here. His canonical polar/rectangular
> point example is uninspiring: you can't even represent (1,1) precisely
> in polar; you can't represent (45 degrees, 1) in rectangular.
 > type definition is an area where you can't get away from the  > limitations of the underlying data structure.

Is this your reasoning? :
To represent polar(45,1) as a cartesian(x,x) we would need an exact way to represent the square root of 2. We don't have that so "you can't represent (45 degrees, 1) in rectangular."

That begs the question: why, exactly? or: is it really impossible?

And, related: is this an implementation issue or a type-model issue? And: is the (current) impossibilty of an implementation enough reason to abandon a model?

((10 divided by 3) times 3) does not give you 10 in any programming language (barring optimization effects :-) It does not realy stop us from thinking of these operators as the ones we are familiar with from math.

Maybe we just need to look for a better set of underlying data structures. Not saying that is easy, though.

> I think it's another place where encapsulation fails when
> you look too closely.
>
> Beyond that, I don't think mixing languages is anything more sublime
> that a simple foreign function interface.

Just guessing here: I suspect programming languages will appear to differ in surprisingly interesting and complex ways. Anyway, we are bound to find out in the coming years. The Parrot project will uncover many of these surprises if they exist.

> And Date's idea that there *not be* a way to define new types in
> the application language is disastrous!

Are you sure?
D&D Tutorial D supports UDT's (User Defined Types) - or am I misunderstanding your statement? Received on Fri Sep 10 2004 - 22:55:55 CEST