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From: bzs@world.std.com (Barry Shein)
Newsgroups: alt.religion.computers
Subject: Re: Shoulds arrays start at zero or one?
Message-ID: <1990Jan19.025020.14568@world.std.com>
Date: 19 Jan 90 02:50:20 GMT
References: <4832@crdgw1.crd.ge.com> <1990Jan18.034728.8696@world.std.com> <4839@crdgw1.crd.ge.com>
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Organization: The World @ Software Tool & Die
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In-Reply-To: shane@underdog.crd.ge.com's message of 18 Jan 90 15:58:31 GMT


From: shane@underdog.crd.ge.com (Randall H. Shane)
>	Y'know, there is a place for a good teaching procedural language --
>one with a reasonable standard functionality like C with its standard
>libraries, but with a simpler syntax, less direct exposure to the assembly 
>language level, and less opportunity for students to slice themselves. 
>Like Pascal should have been, I guess.

Actually, I disagree.

First, I've taught programming at various levels for about a decade.
I've taught courses using, lessee, C, Pascal, PL/I and IBM/370
Assembler and even "If It's Tuesday This Must Be Cobol" (i.e.  Survey
Of Programming Languages, add Lisp, Snobol, Cobol, Algol, Fortran and
a few others to the above list, fun course.)

I don't think it's a good idea to teach in a "teaching language", far
better to think hard and subset a "real" language. When I taught C
people would always say "ugh, how do you get them past all that
complicated pointer syntax?! What an awful language to teach in!"

Well, the answer was of course I simply didn't cover pointers until
they were ready to learn pointers. I also never had as much trouble
with teaching pointers as some of my colleagues seemed to. I suspect
this was at least partially due to the fact that I understood them and
had put a lot of thought into how to explain them.

I usually started with some amusing "confusion between the thing and
the thing contained" stories, like when in the news they report that
"The White House said today..." they don't mean The White House at all
because it cannot talk, they mean the contents of the white house.

Most of the problems people have with pointers has a lot to do with
that sort of sloppiness in our natural languages (not that it's a
problem in natural languages, context saves the day there, but we are
accustomed to using a location to describe its contents as if they
were interchangeable.)

But I digress.

Pascal was initially designed to be a teaching language and it shows.
One of the design goals of the language was merely to be able to write
a one-pass compiler so students wouldn't use so much CPU time
recompiling, back in a day when compiling was a very dear activity.

It's amusing to think that one can design a language that is both
lightweight on the CPU and easy to learn.

Those goals seem terribly at odds to say the least! BASIC suffers from
the same problem (C doesn't only because no one ever claimed it was
particularly easy to learn, it just is because it's a rather clean
design, not because that was the motivation of the designer
especially.)

The whole idea of packed data comes from the odd word size and
word-addressibility of the B6600 Pascal was first designed for. I am
forever amused at the explanations students have been given for this
feature (umm, it's, uh, well, packed, lessee, ah!, more memory
efficient! yeah, must be that...hah! Well, true on some ancient
machines, but not usually the machine being used.)

The lack of external linkage in the standard language is truly quaint
and heralds from an era when linking several source modules on most
operating systems was a heroic feat (hence, no one needed that for
teaching.)

Ever notice that in order to attain portability Knuth's TeX (which is
written in Web which is translated to Pascal) produces one 10,000+
line source file? Not exactly my idea of software engineering.

Unfortunately, so many people were taught Pascal (particularly around
engineering schools who felt they had to move away from Fortran even
by the late 70's) that a market developed for letting them continue to
program in Pascal in their professional careers.

Since these students had grown up now and Pascal was clearly
inadequate to do much anything the vendors responded by extending
Pascal in an effort to capture market.  So Pascal mutated into at
least 50 different dialects, probably more, each usually quite
incompatible. Adding a syntax for variable-length string types is not
minor surgery!

It was all a mistake and most so-called proponents are usually victims
of that mistake trying to rationalize the situation they are in.

I haven't met too many folks, who know several languages well, and
consider Pascal very good. It's passable for little projects, perhaps
less than 1,000 lines of code, but utterly unmanageable beyond that
and truly awful for any projects that require significant interface to
system libraries (again, in its standard form, once you extend it then
the word "Pascal" is merely a marketing tool, if the FDA were in
charge of programming languages they'd forbid those languages from
being called "Pascal", "Pascal-like" perhaps.)
-- 
        -Barry Shein

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