Re: specifications (was Re: Languages: The Bigger the Uglier)

jgm@CS.Cornell.EDU (Gregory Morrisett) writes:
> ...Don't you readily accept the idea of presenting the syntax of a
> language using a BNF grammar (or perhaps even an LALR(k) grammar)?
> Then why protest a formal definition of the semantics, using, say
> structured operational semantics?


Henry Spencer <henry@zoo.toronto.edu> wrote:
>Because most people in this business have been exposed to BNF or the
>equivalent, and find it easy to understand, and neither of these
>statements is true of structured operational semantics. This isn't
>irrational prejudice; if the formal-semantics methods were as simple
>and clear and readable as BNF, they would have been adopted as quickly
>and enthusiastically as BNF was. They haven't been.


I think this underestimates the ``chicken and egg'' problem.


As Henry notes, a lot of folks have seen (and, we hope, kinda
understand) BNF. Why? Because you would be hard pressed to find a
Computer Science curriculum any time in the past 10 (or maybe 20)
years where you could have gotten a Batchelor's and _not_ have been
exposed to BNF somewhere along the way.


So now there are sufficient numbers of people who know BNF that it is
now taken as a given that the syntax of any standardized programming
language will be expressed in BNF... and if you don't grok
BNF... well... tuff luck. (We'll just tell you that you should have
learned that in school.)


So the big question is ``When will we get to the point where everyone
who goes through a CS department... and who comes out still alive on
the other side... will have been adequately exposed to at least _some_
kind of formal semantics notation to allow our standards to be written
using that without losing 90% of the people?''


It's an important question, because as langauges become more
complex... and they ARE getting more complex, as I noted earlier in
this thread... that tired old English prose just ain't making it
anymore. It ain't very precise, and (another important point which is
not often mentioned) in this era of international standards, English
as a language doesn't consistantly cross national boundaries all that
well. (I'd hate to wake up one morning and find out that the folks in
Quebec had been using their own dialect of C, just because they
refused to read the ISO standard due to its unfortunate use of
English. ;-) --


-- Ron Guilmette, Roseville, CA ---- E-mail: rfg@monkeys.com ---
--

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