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From: WONGWF@NUSDISCS.BITNET
Newsgroups: comp.lang.scheme
Subject: PC Scheme
Message-ID: <9006070336.aa15956@mc.lcs.mit.edu>
Date: 7 Jun 90 23:38:00 GMT
Sender: root@athena.mit.edu (Wizard A. Root)
Organization: The Internet
Lines: 38

Hello Everyone,

        First, my 2 cents worth : SCOOPS comes with PC-Scheme. My experience
with SCOOPS is that it makes debugging a little difficult - with all the
indirections, you hardly know where something fails by using the backtrace
facility.

        Now, my problem ... I have been using PC Scheme 3.03 for some time
now and there have been those desperate moment where the interpreter bombs
on me without any valid reasons. The first time it happened, it gave "Timer
already running" or something like that. Well, silly me, I thought to myself,
its probably because I use ENGINES and when my program bombed, it didn't reset
the timer properly.

        Some time later, I was satisfied with my program so I started removing
"writeln"s from it. It bombed. The funny thing was that I narrowed it down to
a particular "writeln" which was of no particular significance - when it is in,
the program worked, without it the program bombed. I went around it by removing
some "write-char" statements (which by the way, was important) together with
that particular "writeln". It worked - or so I thought !

        Now, my program sometime works perfectly well while at other time,
WITHOUT ANY modifications, failed. It usually gives "VM Error - ()" whatever
that means. I did a backtrace but I have no reason to expect it to fail at the
place where it said it did. I am now at the conclusion that PC Scheme is
unstable ! (although I hardly know why) Or maybe I'm using the wrong version.

        Anyone out there have similar experiences ? Perhaps someone could give
me some pointers.


Weng-Fai, WONG,
Dept. of Info. Sys. and Comp. Sc.,
National University of Singapore,
Lower Kent Ridge Road,
Singapore 0511.
Republic of Singapore.
email : wongwf@nusdiscs.bitnet