Re: Embedded Keynote Speaker Mentions Ada

[Benjamin Ketcham <bketcham@drizzle.com>]

In article <upt4emx9k.fsf@no.email.thanks.invalid> Anders wrote:
> "Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca> writes:
> 
>> Benjamin Ketcham wrote:
>> 
>> > How long does someone who actually knows Ada (not me) think it
>> > would take to translate the kernel to Ada?
>> 
>> I think this process is the wrong way to put something into
>> Ada. Ada can be made to look like a C program, but I don't
>> see any benefit to that.
>> 
>> Only by redesign, in Ada terms (not C ones), does such a
>> project have any useful outcome. For this you toss away
>> the C code, and design from the requirements.  And what
>> I am suggesting is that you don't need the Linux kernel
>> to dictate your requirements.
>> 
> 
> I am not a programming lecturer. I got an impression that there are some persons participating in c.l.a who are giving Ada lectures. I want to raise a question about the "useful outcome":
> 
> Couldn't a useful outcome be the learning process that comes out of a study where you rewrite a piece of code in Ada, first as a so called line-by-line translation and then as a programming project where you do it from the requirements?
> The first mentioned step will certainly raise a bunch of questions about the differences between the [programming language] way and the Ada way. The questions are then answered while doing the second step.
> 

Exactly, I see this as a benefit, as well.

But there's another benefit I'd expect in addition to the "polemic"
benefit.  That is, I suspect there would be real interest in an Ada Linux
kernel (or other familiar, high-popularity software item: a version
of, or competitor to, Apache would have a very similar effect, IMO),
from many quarters where reliability is perceived to be especially
important.  I'm not as much thinking of the NSA, etc., as businesses
and individuals who would be swayed by the "Reliability" selling point.
E.g., sites that run FreeBSD or some other "off-brand" Unix, because
they are more concerned with (and knowledgeable about) security issues,
than with going with what's popular or what has a lot of drivers.
(Indeed, maybe *BSD would be a better target for a rewrite in Ada than
Linux, given the security focus and the "against the grain, holier than
thou elitism" (no offense intended) of the BSD folks...)

These benefits accrue specifically for a rewrite/translation of an
existing "popular" piece of software.  A new and different "killer app"
that happened to use Ada would be keen, too, but (a) that's not what
I'm talking about, and (b) where is it, anyway?
If there are real benefits to Ada, they should apply even for a "dumb"
rewrite.  If there are only benefits given a ground-up redesign,
without even matching the same "API" as an existing program, then
are these benefits really due to Ada, or just due to generic software
engineering, and the obvious fact that almost anything can be improved
by a redesign?  Wouldn't such things as bounds checking, and the
nailing down of specific behaviour for a host of exceptional conditions
that the C standard just leaves undefined, bring benefits even to such
a "C-centric" program as a Unix kernel?

> The Linux kernel is of course a too big piece for such a project.

Obviously I disagree here.  Or at least I question, why not the
Linux kernel, or something similarly "ambitious".  If one video
driver happens to be written in Ada, nobody except people here will
know or care.  If a whole kernel, or webserver etc., is written in Ada,
it opens up potential exposure to and interest in the language, to
a much bigger world of programmers.  And the opportunity to directly
compare performance and reliability between the Ada and C versions,
seems seductive to me.  Are people afraid of that comparison?

> Anders

PS:  Are you a relation of Lars W.?  Apologies if this is an FAQ of
your life.

--Benjamin