Re: Language design by by committee ( was Re: Try J# ( was Re: J# is there ))

[Richard Riehle <richard@adaworks.com>]

Ted Dennison wrote:

> In article <dale-400CAE.17165114102001@mec2.bigpond.net.au>, Dale Stanbrough
> says...
> >
> >Israel Raj T wrote:
> >
> >> Tony Hoare was an early member of the design committee until he left
> >> in disgust. In his ACM Turing Award lecture "The Emperor's Old Clothes
> >> " he says just that.
> >
> >Tony Hoare left because he thought the language was way too big.
> >Later on he wrote a foreward to a book in which he recanted this
> >view, and hope people would have the opportunity to use Ada (I
> >think he said "this fine language", but I can't be sure).
>

In a book by David Watt, Brian Wichmann, and William Findlay titled
"Ada Language and Methodology" published in 1987 by Prentice-Hall,
C. Anthony R. Hoare writes, of Ada,

"... a new programming language: 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 ...

"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 ... "

Note that these remarks were published long after the Turing Award Lecture.
However, even in that lecture, Mr. Hoare's criticisms were directed less at
the entire language and more at some specific features he felt were prone
to risky programming practice.  In particular, he was concerned about the
inclusion of exception handling in a language intended for safety-critical
software.  In his view, if a language included built-in exception handling,
programmers would be tempted to misuse it.  That is, instead of writing
robust code, they would too often rely on exception handling.

His concerns, it seems, were prophetic.  In the early days of Ada programming,
and even today, we see exception handling being misued.   This misuse
is not exclusive to Ada.   We too frequently see exceptions misused
in programs written in Java and C++.    Note that the SPARK Ada model
completely eschews the Ada exception handling model in favor of a more
rigorous assertion structure.  Dr. Chapman can probably elucidate on
that point, if anyone wants to know more about it.

Richard Riehle