Re: discriminant questions

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Fri, 30 Sep 2011 12:07:53 +0200, Georg Bauhaus wrote:

> Back on track: my question was whether or not a language should
> enable programmers to implement or override what is built into the
> language core.

It should not.

> Whether or not programmers should be able to correctly manipulate
> language features.

They should not. 

The idea of extensible language was popular in 60s, but then was quickly
ditched.

>> Has the number 12.3 general purpose, or specific
>> to the domain of numbers smaller than 13?
> 
> The sqrt operation is not general purpose in that there is only
> a selection of programs that ever use it.

I bet that practically no program uses the number -435167342. Is it not
general purpose?

>> A "primitive universal computer" runs what? [answer: one or more tasks]
>> Task in the meaning "subject of scheduling" is not only primitive, it is
>> atomic, semantically there is nothing a task could be divided into.
> 
> This definition of task cannot serve the goal of establishing
> program construction facilities of programming languages, and
> of Ada in particular:

I don't understand this.
 
> I'll also prefer "task" to mean something that Ada programmers would
> recognize.

As something, which is not a task?

I don't understand what you are trying to say. Task is fundamental to
concurrent computing, they cannot be expressed in any other terms.

>>> The level of detail in a concept is the biggest factor in "heavy" IMO.
>>> Heavy things might be useful, they might feel right, they might be
>>> efficient (or free).
>>
>> Again, "heavy" is meaningless outside one of three contexts: 1)
>> computational environment ("hardware language"), 2) the programming
>> language, 3) the problem domain.
> 
> Plus: 4) compiler making business requirements,

Irrelevant.

> 5) programmers, customers,

Programmers /= customers

Anyway, you didn't answer which category is supposed to decide what is
"heavy".

> A general purpose programming language will IMHO either
> be a panacea that includes, in its definition, every mechanism ever
> invented,

That would be just a poorly designed language.

> or tries to be minimal in some sense.

This applies to *any* language.

> Should a language like Prolog be defined such that implementers
> must provide for programmers who wish to override the database
> scanning implementation? Or replace the backtracking implementation with
> one of their own?

Yes, if Prolog designers wished it survive... but they didn't.

> Alternatively, the customer/programmer can just have
> a Prolog shop make an implementation the meets their special requirements.

See above. It didn't work in 60s, it has less than zero chances now. For
same reasons we are buying industrially produced things, even if it is
relatively inexpensive things like food or clothing.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de