Re: Ada to C++ translator?

[Marin David Condic <mcondic.auntie.spam@acm.org>]

Thanks for the enlightment. I think my only point was that subsets of Ada existed
back in '83 (or thereabouts) so there isn't something new allowed in Ada that just
became available. As I recall - some of the Ada subset compilers also had the word
"Ada" in them somewhere - nothing wrong with that. I recall the DoD simply having a
concern that someone could start peddaling what they called "Ada" only without a
full implementation. (There were dozens of compilers at the time that called
themselves "Pascal" with no two exactly alike. So what did it mean to call a
compiler a "Pascal" compiler?) They wanted to be sure that if someone sold you a
compiler and called it "Ada" that it in fact implemented the whole of the language.
I don't think the situation is much different today - just maybe not as formal.
People still expect that if you label a compiler "Ada" that it has run the
validation suite and implements the full language.

MDC



Nick Williams wrote:

> Marin David Condic wrote:
>
> >> There's a difference between a compiler which doesn't support the full
> >> language and a project choosing not to use the full language!
>
> > And your point would be? :-) Seriously, I understand there is a distinction,
> > but I don't know that it makes any difference. SPARK is a chosen subset of
> > Ada and I'd presume that if one bought the SPARK compiler that it would
> > compile only the SPARK subset. (Or at least someone might choose to
> > implement a compiler for SPARK that way.)
>
> You'd have difficulty buying the SPARK compiler; as there isn't one :-)
>
> From the Ada perspective, SPARK is indeed a subset; since whatever is a valid
> SPARK program is also a valid Ada program, but the converse does not hold.
>
> However, just because an Ada program uses the subset of the Ada language which
> is valid in SPARK will (most likely) not make that program valid in SPARK: the
> SPARK language has a considerable variety of non-compilable statements (which
> look to an Ada compiler like comments) which are not optional when constructing
> SPARK programs. It also has restrictions on the use of language features which
> can make it harder to prove properties of your program.
>
> > (SPARK doesn't call itself "Ada" and isn't validated, right?)
>
> Well, the 'A' in SPARK does stand for Ada ... and the only validation is
> a relatively detailed and complete formal semantics of the language :-)
>
> Cheers,
>
> Nick.

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Marin David Condic - Pace Micro - http://www.pacemicro.com/
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