| Author |
Message |
Nick Maclaren
Guest
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 Posted:
Fri Aug 19, 2005 2:16 pm Post subject:
Re: ISA-independent programming language |
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In article <7zwtmis31f.fsf@tyr.diku.dk>,
torbenm@tyr.diku.dk (=?iso-8859-1?q?Torben_=C6gidius_Mogensen?=) writes:
|>
|> > Fortran and C++ managed to steer between the Scylla of a hopelessly
|> > ambiguous and incomplete language and the Charybdis of missing the
|> > boat,
|>
|> I'm not sure C++ has avoided being ambiguous and incomplete. I'm
|> willing to accept that it avoided incompleteness, but it is voefully
|> ambiguous.
Not by comparison with C99 :-(
I agree that it is not a shining example (Fortran is better, but
still not good), but it isn't actually unusable. C99, many aspects
of C90, and a large proportion of POSIX really are unusable.
|> > but most attempts to standardise a hacked-together language have
|> > foundered on one or the other.
|>
|> Including that of C++.
Hmm. Would you describe it as actually unusable?
Regards,
Nick Maclaren. |
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Torben Ęgidius Mogensen
Guest
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| Posted:
Fri Aug 19, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
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nmm1@cus.cam.ac.uk (Nick Maclaren) writes:
| Quote: | In article <7zwtmis31f.fsf@tyr.diku.dk>,
torbenm@tyr.diku.dk (=?iso-8859-1?q?Torben_=C6gidius_Mogensen?=) writes:
|> > but most attempts to standardise a hacked-together language have
|> > foundered on one or the other.
|
|> Including that of C++.
Hmm. Would you describe it as actually unusable?
|
No, it was the satement about lack of ambiguity I objected to. While
C++ is nominally standardized, the standard is so complex that (to my
knowledge) no C++ compiler conforms exactly to the standard.
Additionally, the behaviour is in many cases unspecified or
imlementation dependent.
Torben |
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Nick Maclaren
Guest
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| Posted:
Fri Aug 19, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
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In article <7zr7cq0xal.fsf@tyr.diku.dk>,
torbenm@tyr.diku.dk (=?iso-8859-1?q?Torben_=C6gidius_Mogensen?=) writes:
|>
|> > |> > but most attempts to standardise a hacked-together language have
|> > |> > foundered on one or the other.
|> > |>
|> > |> Including that of C++.
|> >
|> > Hmm. Would you describe it as actually unusable?
|>
|> No, it was the satement about lack of ambiguity I objected to. While
|> C++ is nominally standardized, the standard is so complex that (to my
|> knowledge) no C++ compiler conforms exactly to the standard.
|> Additionally, the behaviour is in many cases unspecified or
|> imlementation dependent.
I can assure you that C99 and, to a great extent, POSIX are orders
of magnitude worse. There are large and critical areas where nobody
has a clue even what the intent of the standard is - and I mean in
principle, not just in detail.
C++ has at least made an ATTEMPT to distinguish constraints on the
program from constraints on the implementation. Can you imagine a
standard where there is DELIBERATE ambiguity over whether the
implementor or programmer is required to ensure that something does
or doesn't happen? Well, such standards exist - and it is part of
my job to be a link between the users and the vendors :-(
C++ may be bad, but it hasn't foundered in the way that Algol 68,
Modula 2 and C99 have. It is probably marginally more successful
than POSIX, which isn't exactly an accolade.
Regards,
Nick Maclaren. |
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Guest
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| Posted:
Fri Aug 19, 2005 11:37 pm Post subject:
Re: ISA-independent programming language |
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Nick Maclaren wrote:
| Quote: | In article <1124392489.091561.53190@z14g2000cwz.googlegroups.com>,
wclodius@lanl.gov> wrote:
snip
The standard
uses VDM to provide a very detailed specification. However, the use of
VDM and the definition of a (overly large) library resulted in a
standard an order of magnitude larger than what Wirth considered
necessary. It was a shock to followers of Wirth when his ~50 page
description expanded to 700+ pages when standardized. It was a
disappointment to them that standardization took so long that Modula 2
was no longer in significant use upon completion (94?).
As with Pascal!
Not really. The first Pascal standard came out in the late 70's, while |
Pascal was still popular. Its problem was that it was only a slight
improvement on Wirth's initial description, and hence was severly
limited in its usefulness. Extended Pascal was not only late, but not
as clearly defined as some other languages, and incompatible with many
extensions to Pascal.
| Quote: |
And how compatible was the standard with the Modula 2 that Wirth
exposed to the world?
In theory I believe it was highly compatible with Wirth's description. |
However I suspect it was not very compatible with real world Modula 2
code. Much of the problem I suspect would be duee to Wirth's failure to
define a standard library for Modula 2 (his libraries developed in
"Software Engineering(?)" were suposedly inconsistent from edition to
editon, were never claimed to be standard, and were insufficent for
widespread portability.). Other code may have relied on compiler
specific interpretations of Wirth's description. Reliance on compiler
specific aspects for 1% of the code causes problems for code more than
100 lines long.
> <snip> |
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Nick Maclaren
Guest
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| Posted:
Sat Aug 20, 2005 12:01 am Post subject:
Re: ISA-independent programming language |
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In article <1124476674.377039.295140@g44g2000cwa.googlegroups.com>,
<wclodius@lanl.gov> wrote:
| Quote: |
... It was a
disappointment to them that standardization took so long that Modula 2
was no longer in significant use upon completion (94?).
As with Pascal!
Not really. The first Pascal standard came out in the late 70's, while
Pascal was still popular. Its problem was that it was only a slight
improvement on Wirth's initial description, and hence was severly
limited in its usefulness. Extended Pascal was not only late, but not
as clearly defined as some other languages, and incompatible with many
extensions to Pascal.
|
Eh? I have just checked up to remind myself, and ISO Pascal was only
STARTED about 1977 and wasn't delivered until 1982. By then, it was
essentially just an IBM PC language and the control of the language
had been, er, taken over by Borland. Outside that community, it was
more-or-less defunct.
To make things worse, ISO sorted out the array problems, which
prevented it from being useful for numeric code, but ANSI demanded
a standard without that.
| Quote: | And how compatible was the standard with the Modula 2 that Wirth
exposed to the world?
In theory I believe it was highly compatible with Wirth's description.
However I suspect it was not very compatible with real world Modula 2
code. Much of the problem I suspect would be duee to Wirth's failure to
define a standard library for Modula 2 (his libraries developed in
"Software Engineering(?)" were suposedly inconsistent from edition to
editon, were never claimed to be standard, and were insufficent for
widespread portability.). Other code may have relied on compiler
specific interpretations of Wirth's description. Reliance on compiler
specific aspects for 1% of the code causes problems for code more than
100 lines long.
|
Right. And it is not the only language to make that mistake.
Regards,
Nick Maclaren. |
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Anne & Lynn Wheeler
Guest
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| Posted:
Sat Aug 20, 2005 12:15 am Post subject:
Re: ISA-independent programming language |
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nmm1@cus.cam.ac.uk (Nick Maclaren) writes:
| Quote: | Eh? I have just checked up to remind myself, and ISO Pascal was only
STARTED about 1977 and wasn't delivered until 1982. By then, it was
essentially just an IBM PC language and the control of the language
had been, er, taken over by Borland. Outside that community, it was
more-or-less defunct.
|
in the 70s, one of the vlsi tools group did a pascal for the
mainframe, which was then used to develop some number of internal vlsi
design tools. it was also released (in late 70s) as a mainframe
product (pascal/vs)and later ported to the rs/6000 (big motivation was
ths internal tools). one of the (external) product guys did sit on the
iso committee.
in the early/mid 90s ... some number of the vlsi tools were spun off
to outside companies (that specialized in vlsi design tools) .. and a
lot of these tools had to be ported to other (primarily workstation)
platforms.
the mainframe/rs6000 pascal had quite a bit of work done on it
supporting the major (vlsi design tool) production
applications.
trying to get production applications that were possibly 50k-60k lines
of pascal to some of these other platforms ... was a major
undertaking; especially since these pascals appear to have never been
used for anything other than student jobs (and in at least one case,
the organization had outsourced its pascal support, the organization
was maybe 30 minute drive, depending on traffic conditions ... but the
actual support organization was 12 time zones away).
minor past references:
http://www.garlic.com/~lynn/2004d.html#71 What terminology reflects the "first" computer language ?
http://www.garlic.com/~lynn/2004q.html#35 [Lit.] Buffer overruns
http://www.garlic.com/~lynn/2005e.html#0 [Lit.] Buffer overruns
http://www.garlic.com/~lynn/2005e.html#1 [Lit.] Buffer overruns
--
Anne & Lynn Wheeler | http://www.garlic.com/~lynn/ |
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Nick Maclaren
Guest
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| Posted:
Sat Aug 20, 2005 12:15 am Post subject:
Re: ISA-independent programming language |
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In article <m3wtmhhe2g.fsf@lhwlinux.garlic.com>,
Anne & Lynn Wheeler <lynn@garlic.com> wrote:
| Quote: |
nmm1@cus.cam.ac.uk (Nick Maclaren) writes:
Eh? I have just checked up to remind myself, and ISO Pascal was only
STARTED about 1977 and wasn't delivered until 1982. By then, it was
essentially just an IBM PC language and the control of the language
had been, er, taken over by Borland. Outside that community, it was
more-or-less defunct.
in the 70s, one of the vlsi tools group did a pascal for the
mainframe, which was then used to develop some number of internal vlsi
design tools. it was also released (in late 70s) as a mainframe
product (pascal/vs)and later ported to the rs/6000 (big motivation was
ths internal tools). one of the (external) product guys did sit on the
iso committee.
|
Yes. I was the relevant project manager in SEAS/SHARE Europe/GSE
a bit later. I can assure you that customer interest in that product
was somewhat limited :-)
| Quote: | in the early/mid 90s ... some number of the vlsi tools were spun off
to outside companies (that specialized in vlsi design tools) .. and a
lot of these tools had to be ported to other (primarily workstation)
platforms.
the mainframe/rs6000 pascal had quite a bit of work done on it
supporting the major (vlsi design tool) production
applications.
trying to get production applications that were possibly 50k-60k lines
of pascal to some of these other platforms ... was a major
undertaking; especially since these pascals appear to have never been
used for anything other than student jobs (and in at least one case,
the organization had outsourced its pascal support, the organization
was maybe 30 minute drive, depending on traffic conditions ... but the
actual support organization was 12 time zones away).
|
Quite. I had to port a line-truncated ICL 1900 Algol 60 program
to IBM (Delft) Algol in 1987, which was an interestingly bizarre
exercise. My boss did not realise what a fluke it was that I
knew both dialects - hands up other readers of this group who
can say the same :-)
And Let's stay off Cobol F ....
Regards,
Nick Maclaren. |
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Stephen Fuld
Guest
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| Posted:
Sat Aug 20, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
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|
"Dan Koren" <dankoren@yahoo.com> wrote in message
news:43020f5e$1@news.meer.net...
| Quote: | "David W. Schroth" <David.Schroth@unisys.com> wrote in message
news:ddt12v$2138$1@si05.rsvl.unisys.com...
Anton Ertl wrote:
While we are catering for obsolete architectures, are there still
machines around with non-2s-complement signed integer representations?
Yes, there are.
|
The descendants of the Univac 1100 Series (under newer names) are still
being sold and used productivly by many big customers. They use 1s
compliment integers.
There may be others.
--
- Stephen Fuld
e-mail address disguised to prevent spam |
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mihai cartoaje
Guest
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| Posted:
Sun Aug 21, 2005 12:15 am Post subject:
Re: ISA-independent programming language |
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Hank Oredson has written,
| Quote: | If the programming language supports asking for the size, the language
designer has to think about it.
That was my point.
The language should not support such a construct.
What does "size of a pointer" mean, and why should I care?
|
"size of a pointer" means the number of bytes a pointer occupies in
memory.
By "have pointers", I meant being able to read or write anywhere in
address space, as if a program is in physical address mode and writes
to a video card's memory aperture after reading it's address from the
PCI configuration space.
Some programs do their own memory management, like Quake or the linux
kernel. I know of no way this can be done without the size of pointers
becoming visible. |
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Hank Oredson
Guest
|
| Posted:
Sun Aug 21, 2005 12:15 am Post subject:
Re: ISA-independent programming language |
|
|
"mihai cartoaje" <repstsb@yahoo.ca> wrote in message
news:1124569541.042859.98370@f14g2000cwb.googlegroups.com...
| Quote: | Hank Oredson has written,
If the programming language supports asking for the size, the language
designer has to think about it.
That was my point.
The language should not support such a construct.
What does "size of a pointer" mean, and why should I care?
"size of a pointer" means the number of bytes a pointer occupies in
memory.
|
Assuming pointers "occupy bytes", but again, why should I care?
| Quote: | By "have pointers", I meant being able to read or write anywhere in
address space, as if a program is in physical address mode and writes
to a video card's memory aperture after reading it's address from the
PCI configuration space.
|
That is a much different definition of "pointer" than I'm used to.
| Quote: | Some programs do their own memory management, like Quake or the linux
kernel. I know of no way this can be done without the size of pointers
becoming visible.
|
Oh. Never mind.
You seem to have "pointer" confused with "memory address."
We were talking about very different things.
--
... Hank
http://home.earthlink.net/~horedson
http://home.earthlink.net/~w0rli |
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Hank Oredson
Guest
|
| Posted:
Sun Aug 21, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
|
|
"John Savard" <jsavard@excxn.aNOSPAMb.cdn.invalid> wrote in message
news:43088397.738744@news.usenetzone.com...
| Quote: | On Sat, 20 Aug 2005 21:52:02 GMT, "Hank Oredson"
horedson@earthlink.net> wrote, in part:
"mihai cartoaje" <repstsb@yahoo.ca> wrote in message
news:1124569541.042859.98370@f14g2000cwb.googlegroups.com...
Hank Oredson has written,
That was my point.
The language should not support such a construct.
What does "size of a pointer" mean, and why should I care?
"size of a pointer" means the number of bytes a pointer occupies in
memory.
Assuming pointers "occupy bytes", but again, why should I care?
All things in memory occupy memory. And memory is usually made up of
octets.
|
Um ... well ... Univac 1100 / 2200 memory is made of words.
Same for many other machines.
It's that "usually" thing ;-)
| Quote: | Some programs do their own memory management, like Quake or the linux
kernel. I know of no way this can be done without the size of pointers
becoming visible.
Oh. Never mind.
You seem to have "pointer" confused with "memory address."
We were talking about very different things.
A pointer is usually implemented as a memory address. Even if, in a
language independent of the underlying architecture, the use of pointers
is so restricted as to prevent their being manipulated in ways that
disclose this.
|
Yes, my point exactly. An ISA independent language with
pointers will have to hide such things, or will have to provide
mechanisms for discovering such things as the size of a
pointer. I am still curious why anyone might care.
| Quote: | Presumably pointers cannot even be temporarily saved to a file, if their
size is concealed from the programmer.
|
Yes, exactly.
They might not be in a memory space known to the programmer.
There are many different ways a pointer might be implemented.
My point was that "pointer" is a language abstraction.
Saving one to a file is meaningless, unless the language specifies a
meaning for that operation.
Not all the world is C, Unix and byte addressable memory.
--
... Hank
http://home.earthlink.net/~horedson
http://home.earthlink.net/~w0rli |
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John Savard
Guest
|
| Posted:
Sun Aug 21, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
|
|
On Tue, 16 Aug 2005 15:35:18 GMT, "Hank Oredson"
<horedson@earthlink.net> wrote, in part:
| Quote: | The underlying representation should not be visible.
|
That's true for what you and I would think of as a programming language
independent of instruction set architecture.
But apparently the original poster had some very different ideas.
Perhaps he simply means a dialect of C that would run equally well on an
x86, a DEC Alpha, a PowerPC running in little-endian mode, an Itanium
running in little-endian mode... while allowing you to do all the nasty
tricks provided by the C language.
Thus, all the hardware features _common_ to those architectures are
assumed to be true, and exposed to the programmer. Those that differ are
smoothed over.
John Savard
http://www.quadibloc.com/index.html
_________________________________________
Usenet Zone Free Binaries Usenet Server
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John Savard
Guest
|
| Posted:
Sun Aug 21, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
|
|
On Sat, 20 Aug 2005 16:11:29 GMT, "Stephen Fuld"
<s.fuld@PleaseRemove.att.net> wrote, in part:
| Quote: | The descendants of the Univac 1100 Series (under newer names) are still
being sold and used productivly by many big customers. They use 1s
compliment integers.
There may be others.
|
Except for obscure machines used by the military, it is very likely
there are no others, since for virtually all purposes these days,
microprocessors are used for computing.
Although some of the Control Data machines also used one's complement
integers, building on the Univac experience of their engineers, this was
not true of any Cray machine, for example.
John Savard
http://www.quadibloc.com/index.html
_________________________________________
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John Savard
Guest
|
| Posted:
Sun Aug 21, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
|
|
On Sat, 20 Aug 2005 21:52:02 GMT, "Hank Oredson"
<horedson@earthlink.net> wrote, in part:
| Quote: | "mihai cartoaje" <repstsb@yahoo.ca> wrote in message
news:1124569541.042859.98370@f14g2000cwb.googlegroups.com...
Hank Oredson has written,
That was my point.
The language should not support such a construct.
What does "size of a pointer" mean, and why should I care?
"size of a pointer" means the number of bytes a pointer occupies in
memory.
Assuming pointers "occupy bytes", but again, why should I care?
|
All things in memory occupy memory. And memory is usually made up of
octets.
| Quote: | Some programs do their own memory management, like Quake or the linux
kernel. I know of no way this can be done without the size of pointers
becoming visible.
Oh. Never mind.
You seem to have "pointer" confused with "memory address."
We were talking about very different things.
|
A pointer is usually implemented as a memory address. Even if, in a
language independent of the underlying architecture, the use of pointers
is so restricted as to prevent their being manipulated in ways that
disclose this.
Presumably pointers cannot even be temporarily saved to a file, if their
size is concealed from the programmer.
John Savard
http://www.quadibloc.com/index.html
_________________________________________
Usenet Zone Free Binaries Usenet Server
More than 140,000 groups
Unlimited download
http://www.usenetzone.com to open account |
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Hank Oredson
Guest
|
| Posted:
Sun Aug 21, 2005 4:15 pm Post subject:
Re: ISA-independent programming language |
|
|
"John Savard" <jsavard@excxn.aNOSPAMb.cdn.invalid> wrote in message
news:4308861a.1381613@news.usenetzone.com...
| Quote: | On Tue, 16 Aug 2005 15:35:18 GMT, "Hank Oredson"
horedson@earthlink.net> wrote, in part:
The underlying representation should not be visible.
That's true for what you and I would think of as a programming language
independent of instruction set architecture.
|
Grin.
| Quote: | But apparently the original poster had some very different ideas.
|
Indeed.
| Quote: | Perhaps he simply means a dialect of C that would run equally well on an
x86, a DEC Alpha, a PowerPC running in little-endian mode, an Itanium
running in little-endian mode... while allowing you to do all the nasty
tricks provided by the C language.
|
Perhaps C++ or C# or ...
| Quote: | Thus, all the hardware features _common_ to those architectures are
assumed to be true, and exposed to the programmer. Those that differ are
smoothed over.
|
And thus we do not have an ISA independent language.
Exactly what I've been giggling about ...
--
... Hank
http://home.earthlink.net/~horedson
http://home.earthlink.net/~w0rli |
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