Re: Thoughts and Opinions or something like that

["chris.danx" <chris.danx@ntlworld.com>]

"Jerzy Karczmarczuk" <karczma@info.unicaen.fr> wrote in message
news:3AE6D66A.7A3E09F8@info.unicaen.fr...
> "chris.danx" wrote:
> >
> > Hi, [posting to others //nsgroups Ada & misc// re-instated]
>
> (As you wish, but it has NOTHING to do with Ada, etc... And, anyway,
> I don't read those newsgroups, so if somebody is kind enough to comment,
> it won't reach me)
>

Yes, it will.  I posted to more than one group so i could get a larger volume of
discussion, and i'd noticed that c.l.m is not very busy otherwise i might have
just stuck it there.  It's a personal preference i guess, i don't cross post
that often.



> I remarked, concerning the "problems" with VMs
>
> > > Scheme VMs have GC and tail-call optimization. Java VM has threads.
> > > Icon VM has coroutines (rather: co-expressions). No problems, and
> > > I would add that it is MUCH easier to provide for a more complicated
> > > semantics of a language using an interpreter than compiling to
> > > a native code...
>
> > Do you mean just rip out an interpreter and forget the VM idea
> > until later? That sounds like a good idea.
>
> I think that there is a small misunderstanding here. An interpreter
> IS a Virtual Machine. I just said that in general the idea of building
> a language with interesting semantic layer is easier if one has some
> higher-level executable code, not the assembly stuff, that's all. So,
> if I wanted to construct a language, I would build an interpreter first.
> A virtual machine, if you prefer. My own, not the Java stuff...
>

VM is an interpreter!  Thanks for reminding me, i'd temporarily forgotten that
fact.  I thought you meant that it'd be best to use an interpreter for the
language like Hugs, or Metacombco Basic.  This is what i usually call an
interpreter, but i guess it really doesn't matter, there's so much overlap in
computing.




> Alain Fisher proposes to look at the Smalltalk machine. Yes, it is
> quite powerful, and nice. However, the object-orientation is build
> at a low level, and if you don't need it, there will be a cost.

I don't think I would not use the smalltalk machine.  The cost as you have said
would be too great.

>
> There is plenty of small VMachines around. From Forth/Postscript,
> through the SECD models (including lazy or persistent), the CAMLish
> kernel used e.g. to implement Moscow SML, logical machines such as
> variants of WAM, etc. One can learn a lot from them, even if there
> is not much sense in "ripping" them, and adapting to a novel
> language. In particular one may learn how to implement tail-recursion
> and something about GC.

I wasn't aware of CAMLish kernel, or WAM.  Thanks for the references i'll go
take peek.  Most of the VMs i'd looked at used Stack based methods for
computation but i didn't like that.  I'd never seen a VM use registers before so
i thought i'd do one to see if they're as bad as they've been made out.  It
seems a reverse from hardware computing.

Hardware    Register Performance > Stack Performance
Software    "    "    "    "     < "    "    "    "

Weird!


> > > > -    Lists                         []
> > > > -    Arrays                        <>
> > >
> > > Don't neglect reasonable arrays, please, otherwise one day, sooner
> > > or later you will regret it...
> >
> > What do you mean by reasonable arrays?  What's unreasonable about them?
> >
> > Chris
>
> Not about THEM.
> There are unreasonable arrays simulated by lists. Reasonable mean:
> real arrays, secure (index checking), true random access, working well
> with garbage collector (in some Lisps lists were dynamic, but arrays
> static...), and fast iterators.
>

I would never ever simulate arrays with lists, because of performance.  Having
to walk a list to get to 20th element then re-walk it to get 19th is a bad
thing.  True random access, yes.  secure (index checking) yes!

Don't know about works well with garbage collector but i'd assume so, well i
guess that's a yes then.

Fast iterators?  I know what an iterator is but what is "fast iterator"?  Just a
suped up version of an iterator?

Thanks,
Chris Campbell

>
>
> Jerzy Karczmarczuk
> Caen, France