Re: scripting/extension language for Ada (we have an opportunity here)

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

"Tarjei Tjøstheim Jensen" wrote:
> 
> Robert I. Eachus wrote:
> 
> >
> >    Concept:  Build a special version of gnat for scripting purposes.
> > The syntax will be pure Ada, while there will be some modifications to
> > the semantics to account for the special purpose.  In particular, more
> > implicit conversions will be allowed, and dynamic bindings to
> > environment variables and executable programs.
> >
> 
> You have started in the wrong direction. Such an interpreter should have an Ada-ish
> look and feel, but it should not be Ada. E.g. I strongly believe that it should use
> "[" and "]" for arrays. There should be reasonable defaults.
> 
> The attribute system as found in ada should be simplified. It should be possible to
> write a := a'succ; or something similar and short.
> 
> s1 : string; -- unbounded string
> s2 : string[5]; -- string of maximum length 5, but dynamically sizeable

I have no problem with using [] instead of () for array indexing.
The [] can be easily converted back to () for use in a conventional
compiler.
Along this line, {} can be used for aggregates.
Parsing Ada is notoriously difficult because of the overloading
of () for indexes, subprograms, and aggregates.

<snip>

> 
> >       2) Procedure, function, (and entry?) calls which do not match a
> > subprogram or entry declared in the script will be searched for using a
> > search path.
> >
> >       (Questions:  Use the externally defined path, or a local path then
> > the external path?  Is there a way to call insure that a call is
> > external?)
> 
> It should be possible to specify how to treat certain names and how to search. E.g.
> it should be possible to specify that if a command has a given name, then a given
> command should be executed as in alias in a bash/korn shell. It should be possible
> to specify that if a program cannot be found in a search path, then one should
> search for e.g. program.ksh, program.sh, program.pl, program.py, etc. in the path.

See my previous post on package PATH. External command locations
can be specified with pragma interface_name. External commands
already know how to execute themselves whether they are bash/korn shell,
sed scripts, whatever.

<snip>


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