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From: jbg@sei.cmu.edu (John Goodenough)
Newsgroups: comp.lang.ada
Subject: Hoare, Ada, and safety/complexity
Message-ID: <5076@fy.sei.cmu.edu>
Date: 22 Nov 89 20:54:35 GMT
References: <21248@uflorida.cis.ufl.EDU> <7115@hubcap.clemson.edu> <1415@cs.rit.edu>
Followup-To: comp.lang.ada
Organization: Carnegie-Mellon University (Software Engineering Institute), Pgh, PA
In-reply-to: mjl@cs.rit.edu's message of 21 Nov 89 14:35:58 GMT
List-Id: <comp.lang.ada>


There is a fairly widespread perception that Hoare's Turing Lecture represents
his complete opinion on Ada, as noted in a recent in article, Re: Ada [and the
object oriented metaphor] of 21 Nov 89 14:35:58 GMT mjl@prague.UUCP (Michael
Lutz):

>The mind boggles: Hoare's Turing Lecture concerns about the safety of
>the world have now been compounded by an order of magnitude!  ...

In 1987, Hoare wrote:

    ...an important goal in the design of a new programming language [is] that
    it should be an aid in specification, description, and design of programs
    as well as in the construction of reliable code.

    This was one of the main aims in the design of the language which was
    later given the name Ada.  As a result, the language incorporates many
    excellent structural features which have proved their value in many
    precursor languages such as Pascal and Pascal Plus.

    The combination of many complex features into a single language has led to
    an unfortunate delay in availability of production-quality
    implementations.  But the long wait is coming to an end, and one can now
    look forward to a rapid and widespread improvement in programming
    practice, both from those who use the language and from those who study
    its concepts and structures.

							     C. A. R. Hoare

    [in the Foreword to "Ada, Language and Methodology" by David A Watt, Brian
    A.  Wichmann, and William Findlay, Prentice-Hall, 1987.]

(Of course, the game of "proof by authority" is not all that interesting, but
if you're going to play it, ...)

John B. Goodenough					Goodenough@sei.cmu.edu
Software Engineering Institute				412-268-6391
-- 
John B. Goodenough					Goodenough@sei.cmu.edu
Software Engineering Institute				412-268-6391