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From: staff@cadlab.sublink.ORG (Alex Martelli)
Newsgroups: comp.lang.misc
Subject: Re: The Universal Language
Message-ID: <251@cadlab.sublink.ORG>
Date: 15 Aug 90 21:01:45 GMT
References: <24043@megaron.cs.arizona.edu> <6465@helios.ee.lbl.gov>
Organization: CAD.LAB, Bologna, Italia
Lines: 30

austern@ux5.lbl.gov (Matt Austern) writes:

>In article <24043@megaron.cs.arizona.edu>, gudeman@cs (David Gudeman) writes:
>>I am always disturbed by the idea that for a language to have some
>>good property, it must forbid the programmer from doing X.

>I'm sure that this is obvious to everybody, but I think it bears
>repeating: if the "good property" is efficiency, this is often best
>achieved by forbidding the programmer from using certain
>constructions.

>The more assumptions a compiler can make about a program, the better
>it can do the optimization, and in many cases, the only way a compiler
>can safely assume that a programmer doesn't do something is to make it
>illegal.  (The C calling convention is more complicated than the
>FORTRAN calling convention, for example, because C allows recursion.
...it's actually more the ALIASING that kills you, recursion's no
problem on many machines, it's the darned *aliases*... no matter,
technical quibble, your point is well-taken.

Another property which is well served by language restrictions is
'compile-time checkability'.  It SHOULD be obvious - if you want a
ROBUST code, you make it REDUNDANT, i.e. you 'forbid' many patterns
from the stream so you can detect (and possibly correct) errors...!

-- 
Alex Martelli - CAD.LAB s.p.a., v. Stalingrado 45, Bologna, Italia
Email: (work:) staff@cadlab.sublink.org, (home:) alex@am.sublink.org
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