RE: One language environment don't have future

[Kilgallen@SpamCop.net (Larry Kilgallen)]

In article <mailman.15.1044364570.3911.comp.lang.ada@ada.eu.org>, "Beard, Frank Randolph CIV" <frank.beard@navy.mil> writes:

> I think he's talking about the development environment and not the =
> language.
> Sort of like what DEC did with their systems.  If memory serves me =
> correctly,
> every language (Fortran, C, Pascal, Ada, ...) compiled to an =
> intermediate
> language.  Their debugger looked and worked the same no matter which one =
> you
> were using.  So, when you switched languages, all you really had to =
> learn
> was the new language.

While VMS has a common debugger, it is the object language (from which
executable programs are linked) that is guaranteed standardized.  The
intermediate language within a compiler can be anything the compiler
author chooses.  On VAX there were many code generators although
some language front ends had code generators from the same heritage
(and thus a common intermediate language).  On Alpha, DEC built a
single code generator (GEM) to which their various front ends were
adapted.  On Itanium, the first compiler effort for most languages
is based on an Itanium-targeted GEM, but Intel will later release
a VMS C compiler using the Intel backend for Itanium.

The VMS debugger has a SET LANGUAGE command so that expressions can
be entered in a form "native" to the programming language.  That gets
set automatically if the programmer does nothing, but a programmer
who has stopped at a breakpoint in a Macro or Bliss routine might
want to have their expressions evaluated in Ada or Fortran style.

Currently the GNAT compiler for Alpha VMS uses the GDB debugger
rather than the standard VMS debugger (at DEC's insistance when
they signed the contract to have GNAT ported).  There have been
customer complaints to VMS Development about that, and responses
have been at least that having GNAT use the regular VMS debugger
on Itanium is "under consideration".  In DEC parlance that likely
means "not a p0" (priority).  Doing that on Itanium might be
easier for the GNAT developers since Itanium VMS uses ELF and
DWARF rather than a traditional VMS object format and DST records.