Re: Closures versus objects

On Thu, Feb 15, 2007 at 10:39:14PM +0100, Pascal Costanza wrote:
> 
> As soon as your language is Turing-complete, anything you add is  
> redundant. Language features are always only about convenience.

I contest that. In a theoretical world where only programs and/or values
exist, any Turing-complete language may be equivalent to any other
Turing-complete language. However, in a practical world, where things
besides programs and values exist, there are real differences in what
languages can and can't do which have nothing to do with
Turing-completeness.

For example, to drive the PC's floppy drive controller, you need access
to I/O ports. If your language does not provide such access, you can't
drive the FDC from that language, whether the language is

Turing-complete or not.

Even when language features are only about convenience (which I believe
is the case with closures vs. objects), they make a difference. For
example, I think available language features have a great influence of
what programming paradigms will be common. I also think most people on
this list will agree with me that different paradigms are suitable for
different problems. This means that languages in which certain paradigms
cannot be expressed elegantly cannot be used to solve certain problems
elegantly. This can have very real implications, such as these problems 
not being solved or the programs that purport to solve them being 
unreliable.

To put the above more bluntly and concisely: I think Turing-completeness
is overrated, and that designing a language so that only one or a few
paradigms can be elegantly expressed in it is a mistake.

Regards,

Bob

-- 
That that is is that that is not not, that is, not that that is not.

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