Re: Generic Package

[Markus E Leypold <development-2006-8ecbb5cc8aREMOVETHIS@ANDTHATm-e-leypold.de>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On Wed, 02 May 2007 13:48:26 +0200, Georg Bauhaus wrote:
>
>> On Wed, 2007-05-02 at 12:29 +0200, Dmitry A. Kazakov wrote:
>> 
>>>> Memory is not abstract, addresses aren't abstract,
>>> 
>>> In what sense? 
>> 
>> When you write a Set implementation for a PC, you can specifying
>> addresses and refer to addresses in a consistent way.
>
> But I am not required to do so.
>
> BTW 1, it is a quite common programming pattern to share some predefined
> states of the container, usually empty ones, but not only. An
> implementation of a container of integers could have a reserved
> representation for contiguous ranges of integers. For these it would keep
> only From and To. Now, let you have a container holding 1, 2, 3, can you
> point me the address of 2 there?

You're mixing up sufficient and necessary conditions. But never mind:
your argument is so jumbled anyway -- why bother with logic :-(.

> Another typical pattern is some f applied to the actually kept values, so
> "()" actually is a composition f o "()". So what is in the container?
>
> BTW 2, it is sort of surprising to have such a discussion in c.l.a., for
> Ada was one of the first languages introducing a clear distinction between
> interface and implementation.

Which you have been ignoring all along. The set implementation might
use some natural order on the _representation_ of the items, but need
not expose it. What one sees (interface) is a set. The order would
only be used internally (but one doesn't need even that).

>>> for I in ... loop
>>>    -- what is I'Address here?
>> 
>> irrelevant without computational model. (I didn't say that the
>> mentioned abstract addressable node is good for everything.
>> But even so, it should not be too difficult to come up with an
>> AS-IF model of how I "work"; otherwise, Ada would have an
>> insurmountable teaching problem, besides other exegetic trouble.)
>
> Huh, argumentation to Turing-completeness is a subject of Godwin's Law...

Look, who's speaking ...

>>>> The proof mentions that Count_Var is initially zero and that
>>>> it is only changed by Add_One. Together with the fact that these
>>>> are (1) a local variable and (2) a local procedure
>>>> closely tied this should imply that pre: Count_Var = 0.
>>> 
>>> So, the precondition is not constant true, it is Count_Var = 0? Then either
>>> 
>>> 1. N = 1
>>> 
>>> or
>>> 
>>> 2. The program is incorrect,
>> 
>> The program is correct; the assumption that Count_Var = 0 is
>> false and not the precondition of Add_One at each time. My fault
>> being sloppy.
>> ("Count_Var is initially zero and ... is only changed
>> by Add_One".)
>
> That still does not describe the precondition of. In particular, where it
> follows that counts S and not something else? S have to appear there.

I have not read GBs specification, but just try to understand
mine. There you see explicitely which set you're iterating over. And I
did not have to use any "order" to specify iteration over a set.

>
>> So there is a well defined
>> operation going on
>
> It might be a well-defined operation, but its outcome is not.

The outcome of a well defined operation (I take that as being well
sepcified) does not have to be deterministic.

>
>>> No, first = [whatever] order. It is same.
>> 
>> How is "whatever order" defined, exactly, and how can I say whatever
>> first book will come given a library?
>
> Merely by saying/writing "first." That defines a book.
>  
>>> Ordering is determined by sole existence of the
>>> librarian who can give you a [first] book and continue to do so.
>> 
>> That is, ordering is an outcome of the librarians operation,
>> not of the books.

> Come on, all orderings are ordered but some orderings are more ordered than
> others? (:-)) _WHAT_ is the difference? 

More likely: What is the meaning of your sentence?

> Let you asked somebody to bring
> you books in their "proper" order. 

Other topic. What does "proper" mean here?

> How can you determine if he does not
> cheat, or just mistakenly used the issue date rather than the birth day of
> the author written in Roman numerals and ordered according to Unicode
> positions?

So? I probably asked to get all those books -- on after the other. I
get them. Wether "he" sorts them according to a predefined order or
not -- who cares? Do I _have_ to determine wether he cheats? No: Every
actual sequence of delivery suffices the requirement. And that is the
point you refuse to see.

And by the way: Ignoring what I say doesn't make you right. It makes
it rather seem probable that you stop "discussing" the moment you're
asked to put your cards upon the table and own up to your claims.

Regards -- Markus