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From: thomsen@trwspf.TRW.COM (Mark Thomsen)
Newsgroups: comp.lang.modula2
Subject: Re: Modula2 for Apollos and  Ada,Modula2 question(s)
Message-ID: <440@trwspf.TRW.COM>
Date: Fri, 25-Sep-87 21:21:47 EDT
Article-I.D.: trwspf.440
Posted: Fri Sep 25 21:21:47 1987
Date-Received: Sun, 27-Sep-87 09:52:00 EDT
References: <281@mv03.ecf.toronto.edu>
Reply-To: thomsen@trwspf.UUCP (Mark Thomsen)
Organization: TRW - Data Systems Lab., Redondo Beach, CA
Lines: 53
Keywords: Modula2  Apollo  Ada

In article <281@mv03.ecf.toronto.edu> apollo@ecf.toronto.edu (Vince Pugliese) writes:
>        One question before I go.  Are developers using Modula2 as a
>prototyping tool for, if you will, Ada programming?  I guess
>the reason why ask this is that there seem to be a number of rather
>inexpensive Modula2 compilers available thus making this language more
>accessible to more users.  Another thing is, or was, Modula2 intended
>for the development of embedded real-time applications, much like Ada is and was?


This is one of the great questions of our era in software engineering - whither
Ada and Modula-2.  I am in an aerospace company (thus Ada is important) and
also in a front-end R&D organization within that company.  We use Modula-2
extensively within our environment because it is cost effective when buying
compilers, when buying development environments, when training people to use
it, when developing multiple-processor operating systems, when developing
algorithms, and when integrating new hardware.  It is not a sub-Ada in any
meaningful sense, though we sometimes call it "Ada Lite" and "Real-Time Ada"
to emphasize that it is the best subset of what is really essential.  We get
pressure to use Ada but no extra money to buy the equipment or spend the extra
effort to develop the software.

It is not that Ada is a bad language per se (we each have an opinion on that).
For us it is a more cost effective language that provides the advantages of Ada
(encapsulation & separate compilation, modern syntax, single processor
concurrency, low-level programming) without the excess features.  A customer of
ours pointed out that if Modula-2 was developed 2 years earlier, Ada probably
would not have been developed.  (The less kind may point out that Modula-2
would become Ada in that case.  Comments?)

Your are dead on with the observation that the two languages are for the same
types of applications.  If the DoD asked me I would say mandate Modula-2 for
those programs that Ada seems suitable -- it appears to really be better for
developing real-time, multiprocessor applications (again, I do not say Ada is
a bad language; its just that Modula-2 is better for almost every software
engineering situation I have come across).

By the way, the languages come from almost exactly the same time, have almost
exactly the same rationale and understanding of the software engineering
problem, and have lots of the same syntax.  The only features of Modula-2 that
are not in Ada in equivalent form are procedure variables, sets, and opaque
types (someone challenge this if you disagree -- I would be very interested
in updating my study of this).  John Oglivie in Provo wrote a Modula-2-to-Ada
translator for his masters thesis.  If you wish to use Modula-2 as a precursor
to Ada, you may want to get in touch with John.

This has been long enough.  Does anyone have comments on the relative merits of
the two languages in a constructive sense?


                                         Mark R. Thomsen

The opinions are the author's own and do not reflect TRW's commitment and
considerable support for the use of a common language for DoD procurements.