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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: Ada safety road Was: Which is right ...
Date: 1999/06/08
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In article <wcc674yh8ut.fsf@world.std.com>,
  Robert A Duff <bobduff@world.std.com> wrote:
> Hyman Rosen <hymie@prolifics.com> writes:

> Yeah, and I think the lesson for language designers is to try
> pretty hard to avoid language features with unpredictable
> semantics.

It is easy to get in semantic knots on this issue. For example,
it is reasonable to require a compiler to implement semantics
where it is not predictable from the language what semantics
will be implemented, but it is unreasonable to require a
compiler to implement unpredictable semantics (subtle but
important difference).

Once at an Algol-68 meeting, Gerhard Goos asked exactly what
undefined meant. Someone replied that it meant "unimaginable
chaos", whereupon, Gerhard enquired as to just exactly how he
was expected to implement "unimaginable chaos" in his compiler
:-)



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