Re: Would an *AdaScript* language be a good / bad idea?

[Florian Weimer <fw@deneb.enyo.de>]

dewar@gnat.com (Robert Dewar) writes:

> For the most part, the distinction between scripting languages and
> general purpose programming languages is bogus (and ends up being an
> excuse for some extraordinarily poor language design flying under
> the "scripting language" banner).

;-)

As a rule of thumb, most people consider something to be a scripting
language if it fulfills one or more of the following criteria:

  - You can run the script as if no compilation is necessary.

  - It is not feasible to implement the run-time environment mostly in
    the language itself (either due to language constraints or
    performance).

  - There is no proper specification of the language.

  - There is only one widely accepted implementation, which mostly
    avoids compatibility problems.

  - The language evolves constantly, often losing backwards
    compatibility.

  - It is possible to embed a language implementation in other, "real"
    programs.

  - There is no such thing as erroneous execution.

Of course, these rules are completely bogus, too, but I think those
rules catch the spirit of scripting languages rather well.

> When I say that we use Ada "as a" scripting language, what I mean is
> that we use Ada as a (perfectly satisfactory) language for achieving
> the kind of thing that is often done in a scripting language (by the
> way such languages often come along not only with bad designs, but
> bad software practices, including sloppy design and lack of proper
> documentation).

One nice thing about those scripting languages is the lack of
erroneous execution.  For example, I'm quite confident that the dozens
of Emacs Lisp packages I use do not crash Emacs.  I might lose some
data in the current buffer if I use them, but unless the package is
extremely poorly written, I won't lose an important message I'm typing
in another buffer.

That's why I think that dynamically loading, say, Ada code in an
editor instead of using a scripting language is not advantageous per
se.