Re: scripting/extension language for Ada (was : Re: tagged types extensions)

["Samuel T. Harris" <samuel_t_harris@Raytheon.com>]

Lionel Draghi wrote:
> 
> "Samuel T. Harris" wrote:
> >
> ...
> >
> > It occurs to me that an Ada interpreter can dispense with
> > many of the compile-time checks, relying instead upon a real
> > compiler to "verify" the script source is correct Ada.
> > This alone would enable an interpreter to simply expand
> > generics like macros and not bother with all the checks
> > concerning the instantiation.
> This is a good idea. But i am not optimist enough to think that even Ada
> run time checks could be enforced in a reasonably sized interpreter. But
> this is the goal.
> Another question is : should this script language be strictly compatible
> with Ada? Isn't there any short form that could be effective, and that
> prevent from direct recompilation with an Ada compiler?
> For example, it could make sense to consider Ada.Text_IO, or a Pattern
> Matching package implicitly "whithed" (and maybe even "used"!).

Taking a convenience lesson from the Rational R1000, when one
opened a command window (i.e. where one would enter operating
system commands) it the window initialized with a template
of a parameter-less Ada procedure with the most common
packages already withed. One simply enter the bits of
Ada code to fill in the procedure and away you went.
To this day I don't know how they compiled/linked/ran
such things so fast, but it was the fastest turn-around
I've ever seen. Given the now antiquated hardware Rational
used, I am still impressed with its performance as compared
to contemporary compilation/linking systems of today.

As to you questions, I'd say YES! Why would I want anything
similar to Ada. A subset would be acceptable, but any script
must be compilable. In this way, the scripting language
could be used for rapid prototyping things which will
eventually be compiled. Also, how many scripts have your
written which you wished would run faster? Ada scripts
can be later compiled for greater performance, albeit
taking more disk space :)

> >
> > If I recall correctly, the old Ada-Sage (now Sage-ST) did
> > include a very limited Ada interpreter. This allowed one
> > to quickly prototype the database interface with simple
> > controlling code with very rapid turn-around. Just the
> > sort of thing one needs with hashing out the user
> > interface on-line with the customer.
> Is it available?

There is an Sage-ST site which provides downloads but INEL
which produced AdaSage was a contract based organization.
They would port the system to any compiler/system for
a fee. I haven't been to the site lately so you'll have
to check yourself. Last time I looked the supported
compiler list was getting rather obsolete.

> 
> ________________________________________________________________________
> Lionel Draghi                                          http://attac.org/

-- 
Samuel T. Harris, Principal Engineer
Raytheon, Aerospace Engineering Services
"If you can make it, We can fake it!"