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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Math on dimensioned quantities
Date: 1996/07/10
Message-ID: <DuCH82.6r0@world.std.com>#1/1
X-Deja-AN: 167648441
references: <9607091345.AA03915@most> <DuB08H.2HI@world.std.com>
 <JSA.96Jul10135751@organon.com>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-07-10T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <JSA.96Jul10135751@organon.com>,
Jon S Anthony <jsa@organon.com> wrote:
>> to declare lots of "is <>" functions, but I think it does solve the
>                     ^^^^^^^ abstract
>
>Ooops!  Does this mean you favored the preliminary box notation?

Oops indeed!

No, I definitely prefer the "is abstract" notation.  The above "typo"
was just an embarrassing slip.  I also like the fact that abstract types
are marked explicitly by syntax, whereas in the old "is <>" version of
the language, a type was abstract based on what operations it had
(specifically, if it was tagged, and had some abstract ops, then it was
abstract).  And finally, at the time these changes were made, the rules
for generic formal abstract types were improved.

Interesting, that a minor syntax change from "is <>" to "is abstract"
would trigger some deeper changes as well.

By the way, there was a lot of argument about new reserved words added
for Ada 9X, which I thought was rather silly.  Norman Cohen was the
master of producing new semi-sensible syntax, without introducing new
reserved words.  I was never quite sure how tongue-in-cheek he was
being, but I believe he did suggest "is abs".

- Bob