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Date: 20 Aug 92 23:37:00 PST
From: scheme@mc.lcs.mit.edu
Subject: Scheme Digest V4 #222
To: "pothiers" <pothiers@aries>

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Scheme Digest               Fri, 21 Aug 92       Volume 4 : Issue 222 

Today's Topics:
                        Binary representation
           Common Lisp is a dpANS in Public Review (3 msgs)
                 random rant on random files (5 msgs)
                 Scheme introduction article (2 msgs)
                            scheme update
                        Small Language Wanted
----------------------------------------------------------------------

Date: Thu, 20 Aug 92 17:59:20 GMT
From: Technically Sweet <thinman@netcom.com>
Organization: International Foundation for Internal Freedom
Subject: Binary representation
Message-Id: <vy#nk3h.thinman@netcom.com>
To: scheme@mc.lcs.mit.edu

tmb@arolla.idiap.ch (Thomas M. Breuel) writes:

>It is also trivial to build a store interface on top of binary
>streams. One question is what the language should provide. I'd prefer
>to see it provide binary streams, not stores, since I feel that binary
>streams are more general.

The ASN.1 for binary stream representation of trees gives
most of what is needed.  It's the inter-layer encoder (sort of)
for the OSI suite, and thus has that meaningless aura of 
standards legitimacy which helps in promoting something
new as a standard.  "Look!  It builds on previous standards!"

ASN.1 represents trees according to a pre-specified tree grammar.
A simple "reference leaf" would suffice to encode arbitrary di-graphs.
I think all of the other basic types of Scheme are already
supported directly; there's a compact encoding for small numbers.

All in all, adopting an ASN.1 representation for Scheme gives
a handy binary stream format for files, persistent Scheme systems,
and network I/O.


-- 

Lance Norskog

Data is not information is not knowledge is not wisdom.

------------------------------

Date: Thu, 20 Aug 1992 19:27:58 GMT
From: Clinton Hyde <chyde@pecos.ads.com>
Organization: Advanced Decision Systems, Mountain View, CA 94043, +1 (415)
Subject: Common Lisp is a dpANS in Public Review
Message-Id: <CHYDE.92Aug20142758@pecos.ads.com>
Newsgroups: comp.lang.lisp,comp.lang.clos,comp.lang.misc,comp.object,comp.std.misc,comp.lang.scheme,comp.ai
To: scheme@mc.lcs.mit.edu

this is cool. how about if an electronic copy (which I understand to
be both Tex and DVI versions) gets into an anon-ftp site?

 -- clint
--

Clint Hyde              "Give me a LispM or give me death!" -- anonymous

Advanced Decision Systems       Internet:  chyde@chesapeake.ads.com
2111 Wilson Blvd #800
Arlington, VA 22201             (703) 875-0327

------------------------------

Date: Thu, 20 Aug 1992 19:34:36 GMT
From: Chuck Fry <chucko@kronos.arc.nasa.gov>
Organization: Recom Technologies, NASA Ames Research Center, Moffett Field, CA
Subject: Common Lisp is a dpANS in Public Review
Message-Id: <1992Aug20.193436.28044@kronos.arc.nasa.gov>
Newsgroups: comp.lang.lisp,comp.lang.clos,comp.lang.misc,comp.object,comp.std.misc,comp.lang.scheme,comp.ai
To: scheme@mc.lcs.mit.edu

In article <CHYDE.92Aug20142758@pecos.ads.com> chyde@pecos.ads.com (Clinton Hyde) writes:
>this is cool. how about if an electronic copy (which I understand to
>be both Tex and DVI versions) gets into an anon-ftp site?

I was just thinking that once it becomes a standard, it should be
available on CD-ROM, preferably with a KWIC index and a (reasonably)
portable accessor program written in CL, and tied to the DOCUMENTATION
mechanism already in the language!  Any takers?

 -- Chuck Fry  Chucko@charon.arc.nasa.gov
    Chair, Lisp Users and Vendors '93 conference

------------------------------

Date: Thu, 20 Aug 1992 22:34:45 GMT
From: Clinton Hyde <chyde@pecos.ads.com>
Organization: Advanced Decision Systems, Mountain View, CA 94043, +1 (415)
Subject: Common Lisp is a dpANS in Public Review
Message-Id: <CHYDE.92Aug20173445@pecos.ads.com>
Newsgroups: comp.lang.lisp,comp.lang.clos,comp.lang.misc,comp.object,comp.std.misc,comp.lang.scheme,comp.ai
To: scheme@mc.lcs.mit.edu

I don't know about the CD-ROM part, but the rest of the idea sounds
good. 

if one were to do the CD-ROM part, it should probably include beaucoup
other ANSI std dox also, for many other prog languages (none of which
are even half as cool as Lisp, but there are masochists who use them
anyway).

what would be WAY cool is if there were a gnu-emacs texinfo file of
CLtL2, the ANSI std version, etc.

 -- clint
--

Clint Hyde              "Give me a LispM or give me death!" -- anonymous

Advanced Decision Systems       Internet:  chyde@chesapeake.ads.com
2111 Wilson Blvd #800
Arlington, VA 22201             (703) 875-0327

------------------------------

Date: 19 Aug 92 16:56:19 GMT
From: Ken Dickey <kend@data.rain.com>
Organization: Microtek DSD, Hillsboro, OR
Subject: random rant on random files
Message-Id: <704@data.rain.com>
To: scheme@mc.lcs.mit.edu

tmb@arolla.idiap.ch (Thomas M. Breuel) writes:


>What is wrong with binary streams?

Nothing.  But Scheme is not a store description language (like C/C++),
and does not have a binary interface defined.  I have no problems with
making a "location pointer" and reading memory with a port interface.  
I prefer not to have to reset such a pointer at every random i/o.

It is trivial to build a port interface on top of stores.


-Ken

------------------------------

Date: 19 Aug 92 16:48:54 GMT
From: Ken Dickey <kend@data.rain.com>
Organization: Microtek DSD, Hillsboro, OR
Subject: random rant on random files
Message-Id: <703@data.rain.com>
To: scheme@mc.lcs.mit.edu

bh@anarres.CS.Berkeley.EDU (Brian Harvey) writes:


>Okay, so what do I do if I want to write a new file from scratch?

The same old way.  Open a file, write to it (as a stream), close it.
The current store proposal does not address file extension.

>The part about unsigned-integers-only seems a little user-unfriendly
>to me.

This is a systems programming level.  An implementation can use it
to build higher-level interfaces which do representation mapping
(to/from binary) for you.

>I mean, how does someone write a bignum into a store?

Well you could do (number->string) and store the bytes.  I don't think
that there will be standard binary exchange representations soon
(although MIT Scheme seems to do a pretty good job here).  What I want
is to be able to do representation mapping that **does not depend on
the underlying Scheme's representations**.  [I also do low-level
systems programming, where fixed buffers are very useful (e.g. for an
I/O interrupt).]

>Alternatively, maybe every primitive type has to have an unambiguous
>binary representation the same as it has a print form, and instead of
>explicitly mentioning types you just leave that argument out and
>Scheme figures it out.  That would mean, though, tagging everything
>in the store with its type.

Again, the point is to have a baseline so that this can be done in a
portable manner.

>I'm feeling a little disorganized about this message, but it's because
>I'm really struggling to make sense of the whole idea.  I mean, files
>just feel very different from memory to me.  I know that at some level
>of abstraction they're the same, but they perform quite differently.
>I don't understand [I'm not being sarcastic] the principle of language
>design whereby symbols and strings are treated separately but files
>and memory are treated the same.

Well, it is a abstraction.  Its a bit like thinking of indexes of disk
storage blocks and the blocks they reference as a continuous stream of
characters called a "file", which is certainly a useful abstraction.
After all, why treat disk storage blocks differently?

-Ken

------------------------------

Date: Thu, 20 Aug 1992 15:55:11 GMT
From: Aubrey Jaffer <jaffer@zurich.ai.mit.edu>
Organization: M.I.T. Artificial Intelligence Lab.
Subject: random rant on random files
Message-Id: <JAFFER.92Aug20105511@camelot.ai.mit.edu>
To: scheme@mc.lcs.mit.edu

In article <1992Aug17.100735.7594@physiol.su.OZ.AU> john@physiol.su.OZ.AU (John Mackin) writes:

   In article <9208130624.1.11214@cup.portal.com>,
           vanMeule@cup.portal.COM writes:

   > I feel a little upset at Scheme for lack of direct support in 
   > most Schemes for random files.

   Without in any way endorsing the original poster's desire to make
   Scheme into the new COBOL :):), I too was surprised and disappointed
   that R4RS Scheme doesn't have a seek function to apply to ports.  I
   have an application where I need to read a (large) file line-wise
   backwards, and the only Scheme I can code it in at the moment is
   Scheme->C where I have access to libc.

scm4a10 offers:

  (file-position <port>)                                procedure

Returns the current position of the character in <port> which will
next be read or written.  If <port> is not open to a file the result
is unspecified.

  (file-set-position <port> <integer>)                  procedure

Sets the current position in <port> which will next be read or
written.  If <port> is not open to a file the action of
file-set-position is unspecified.  The result of file-set-position is
unspecified.

------------------------------

Date: 20 Aug 92 22:13:14 GMT
From: "Thomas M. Breuel" <tmb@arolla.idiap.ch>
Organization: IDIAP (Institut Dalle Molle d'Intelligence Artificielle
Subject: random rant on random files
Message-Id: <TMB.92Aug20181314@arolla.idiap.ch>
To: scheme@mc.lcs.mit.edu

In article <704@data.rain.com> kend@data.rain.com (Ken Dickey) writes:

   tmb@arolla.idiap.ch (Thomas M. Breuel) writes:

   >What is wrong with binary streams?

   Nothing.  But Scheme is not a store description language (like C/C++),
   and does not have a binary interface defined.  I have no problems with
   making a "location pointer" and reading memory with a port interface.  
   I prefer not to have to reset such a pointer at every random i/o.

   It is trivial to build a port interface on top of stores.

It is also trivial to build a store interface on top of binary
streams. One question is what the language should provide. I'd prefer
to see it provide binary streams, not stores, since I feel that binary
streams are more general.

                                Thomas.

------------------------------

Date: Thu, 20 Aug 92 17:52:16 GMT
From: Technically Sweet <thinman@netcom.com>
Organization: International Foundation for Internal Freedom
Subject: random rant on random files
Message-Id: <my#njwg.thinman@netcom.com>
To: scheme@mc.lcs.mit.edu

jaffer@zurich.ai.mit.edu (Aubrey Jaffer) writes:
>scm4a10 offers:

>  (file-set-position <port> <integer>)                 procedure

Wouldn't that be (file-position! <port> <integer>)?

Mindless consistency is a virtue in this arena.

-- 

Lance Norskog

Data is not information is not knowledge is not wisdom.

------------------------------

Date: Thu, 20 Aug 1992 15:52:09 GMT
From: Robert Goldman <rpg@cs.tulane.edu>
Organization: Department of Computer Science, Tulane University
Subject: Scheme introduction article
Message-Id: <RPG.92Aug20095209@clones.cs.tulane.edu>
To: scheme@mc.lcs.mit.edu

I am going to be teaching our AI course this semester in Scheme.
I would like to make available to my students (put on reserve at the
library, probably) an article which gives a short, conceptual
overview of Scheme.  Preferably this should be the kind of article
that might appear in CACM or Byte:  not for the layman, but not an
article which discusses denotational semantics, either.  If any of
you know of such an article, I would appreciate any pointers you
could offer.  The LISP FAQ file has a helpful list of texts, but no
overview articles.

Thanks,
R

------------------------------

Date: 20 Aug 92 15:02:30 GMT
From: Robert Goldman <rpg@cs.tulane.edu>
Subject: Scheme introduction article
Message-Id: <2675240@aplvax.msfc.nasa.gov>
To: scheme@mc.lcs.mit.edu

Nntp-Posting-Host-[nntpd-15941]: clones
Reply-To: rpg@cs.tulane.edu (Robert Goldman)
Organization: Department of Computer Science, Tulane University
Distribution: comp
Date: Thu, 20 Aug 1992 15:52:09 GMT

I am going to be teaching our AI course this semester in Scheme.
I would like to make available to my students (put on reserve at the
library, probably) an article which gives a short, conceptual
overview of Scheme.  Preferably this should be the kind of article
that might appear in CACM or Byte:  not for the layman, but not an
article which discusses denotational semantics, either.  If any of
you know of such an article, I would appreciate any pointers you
could offer.  The LISP FAQ file has a helpful list of texts, but no
overview articles.

Thanks,
R

------------------------------

Date: Thu, 20 Aug 1992 09:19 MET
From: LKS@kunrc1.urc.kun.nl
Subject: scheme update
To: Scheme%mc.lcs.mit.edu@mintaka.lcs.mit.edu
Message-id: <01GNSSI4BQCW90NGGW@KUNRC1.URC.KUN.NL>

anyone who can tell me about an update of macscheme 2.0 or can give me
the address and tel of semantic microsystems ?

Thanks,

h. pinxteren

email: lks@kunrc1.urc.kun.nl

------------------------------

Date: 20 Aug 92 08:05:07 GMT
From: Greg Wilson <gvw@epcc.ed.ac.uk>
Organization: Edinburgh Parallel Computing Centre
Subject: Small Language Wanted
Message-Id: <41910@skye.dcs.ed.ac.uk>
Newsgroups: comp.lang.misc,comp.lang.logo,comp.lang.scheme,comp.lang.forth,comp.edu
To: scheme@mc.lcs.mit.edu

[apologies if this is a re-post --- problems first time around]

Hello.  I am looking for a small language to use and modify for teaching
purposes.  Features I want include:

* small, simple implementation in C (at most one week for a senior
  student with a C/Unix background to read and understand source).

* very simple syntax --- preferably only a single syntactic form,
  like Scheme, Logo, and Forth.

* textual scoping of variables (which (sigh) rules out Logo itself)

* logical, integer, floating-point, and string data types (I'm
  happy to have single characters treated as 1-length strings)

Other features that would be nice include

* objects (something simple, like Object Logo, would do --- I
  regularly lambast physicists for using "old" languages like Fortran,
  so I feel I should set a good example for students by using some
  modern ideas myself)

* a source-language debugger

* the ability to cross-call C

Note that a compiler is not needed; performance is not a primary
concern, so interpretation would be fine. 

Any help would be much appreciated.

Thanks in advance,

 ========================================================================
  Gregory V. Wilson                    ||  For in much wisdom is much
  Technical Coordinator                ||  grief; and he that increaseth
  Edinburgh Parallel Computing Centre  ||  knowledge, increaseth sorrow.
  gvw@epcc.edinburgh.ac.uk             ||               - Ecclesiastes
 ========================================================================

------------------------------

End of Scheme Digest
******************************