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

[Ray Blaak <blaak@infomatch.com>]

Pascal Martin <pascal.martin@iname.com.nospam> writes:
>Robert A Duff <bobduff@world.std.com> wrote:
> >> As Robert A Duff said :
> >> "Scripting languages should encourage programs that are easy to
> >> write, easy to understand, and easy to change."
> > 
> > I don't think *I* said that.  In fact, my opinion is that "easy to
> > write" not important; the other two goals I agree with.

Actually, I wrote that. I agree that maintenance is the most important
consideration, but I want it all.

By easy to write, I do not mean the using a terse symbology of C-like or APL
operators. By mean the ability to naturally express powerful high-level
abstractions with a minimum of effort. That is, the language style encourages
such things. Lispy, functional languages usually do well for me here.

By writing things at a higher level, I believe that code is actually clearer
and easier to maintain.

> It seems to me that everytime I chose to use a scripting rather than
> a compiled language, it was for a subset of the following reasons:
> 
> 1- [...] development comfort. 2- Very flexible string manipulation [...]  
> 3- Easy to use regular expression engine. 4- System operations must be easy
> 5- Symbolic indexing [...] 6- Dynamic table resizing. 7- Very portable [...]
> 8- Include a GUI toolkit. [...] Plus: Garbage collection is basically
> mandatory

Very important considerations for me too. I would add flexible data structure
manipulation in general, with strings being one of the most important. Perl is
my favourite for regular expressions, although there are drawbacks for clarity
and maintenance.

> Among the scripting languages/interpreters I have used:
> 
> the ugliest: command.com
> the slowest: sh

I believe these are the worst simply because it is so difficult to express any
reasonable programming task.

> the most confusing: perl
> the most difficult to debug: Tcl (still using it, through, because of Tk :-)
> the most obscure: VAX/VMS DCL (all these optional parameters.. )
> the worst limitations: Microsoft Basic on TRS80 (I liked it at the time)

I use Visual Basic for testing scripts. While it is actually fairly readable,
and one can do Windows COM stuff fairly easily, I despise it, due to major
stupidities in the language (a = b vs Set a = b, line continuations -- for
comments too! one can do "Set a = Nothing" and then "Doit a" but not "Doit
Nothing", etc.).

I actually like Perl a fair bit, since at least one can take the trouble to
write clear code and it is powerful.

My current favourite is scsh due to its coolness.

Do ML or Haskell shells exist? It would be interesting to see how implicit
static strong typing makes things more correct while style allowing for easy
writing of command scripts.

-- 
Cheers,                                        The Rhythm is around me,
                                               The Rhythm has control.
Ray Blaak                                      The Rhythm is inside me,
blaak@infomatch.com                            The Rhythm has my soul.