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From: gjc@mitech.COM
Newsgroups: comp.lang.scheme
Subject: Fixing the order of evaluation. Minimizing the unexpected.
Message-ID: <9104041629.AA19876@schizo>
Date: 4 Apr 91 15:24:09 GMT
Article-I.D.: schizo.9104041629.AA19876
Sender: daemon@athena.mit.edu (Mr Background)
Reply-To: gjc@mitech.com
Organization: The Internet
Lines: 49

Odd numbered arguments right to left and even ones left to right?

Of course that was proposed as just about the most stupid thing that
anybody could think of. (What if somebody said, *yes*?)

But lets be practical. Undefined order of evaluation, (undefined *anything*
really) is one of the big things that gets in the way of most people learning
a computer language. 

OK. Order of evaluation may be undefined. However,

I ASK: *What* useful thing has the person who learns this
fact of (some) computer languages REALLY LEARNED? Is it a reasonable stepping
stone in intelectual developement?

(To never trust the computer? To always be on the look out for ways it might 
screw you?)

[Come to think of it. That is why it it took me only 10 minutes to learn
how to program effectively in MACLISP. There were no special cases and
exceptions to learn, nothing that got in the way of my previous
experience of western/mathematical culture. Subtle implementation
artifacts came up only in the more advanced areas.]

Do most people who may be able to use a computer language give a tinkers damn
about what some compiler-writing person knows? Or what some group of language
implementors think they know about programming style?

Face it. People understand the written word, and written directions
are given to people in this format: LEFT-TO-RIGHT, TOP-TO-BOTTOM.
Period, fact of life. (Yes, there are some right-to-left languages,
but no bottom-to-top languages. And even our common western experience
includes a NUMERIC representation stolen from an Arabic culture,
which is right-to-left. And the confusion this has caused is even
reflected in our COMPUTER HARDWARE, the silly Big-Endian, Little-Endian
crap.)

Does the community of Scheme programmers really gain enough from having
an undefined order of evaluation of arguments to a procedure?
Does it gain enough to make up for the losses faced as people learn
the language. (Or in the long run, less usage of the language).

I could be convinced!

-gjc

p.s. For example, in a spread-sheet the "order-of-evaluation" could very
well be undefined, or at least be something that it is not a good idea
to make use of in a complex program.