Re: Ada "library only" compiler ?

[Brian Drummond <brian@shapes.demon.co.uk>]

On Sat, 21 Jul 2012 10:47:26 -0700, Patrick wrote:


> The Lua team does not
> bless more then a tiny set of libraries(just a few thousand lines) and
> there is no official way to do many things such as serializing data.
> 
> My Lua experience has left me shell-shocked and worried about using a
> lot of the Ada libraries. It took a lot of time to learn various Lua
> libraries and after finding two or three crappy ones in a row, it got
> frustrating. I am not saying that the same thing will be true for Ada
> but it might be nice if all the Ada binding code was in a certain place.

If the language developers do not (much) endorse Lua libraries, then the 
available libraries are likely to be poor!

Ada is strongly intended to support code re-use. Its package facilities 
encourage design for re-use, and re-using already-proven code is one good 
way to reduce the defect rate in a program.

So I would expect your experience with Ada libraries to be better.

(Perfection is not guaranteed however. There don't seem to be many uses 
of the AVR-Ada libraries supporting the AVR processors yet. So I am 
finding missing or incorrect features in some of these, but so far they 
are easy to find or fix)

> I like Lua still but if I am going to use it again, I am going to mix C
> libraries and Lua and pretty much forego the Lua libraries. It's easy
> enough to do this as Lua and it's tiny libraries are easy to keep
> separate.

Rather than writing a C library, it's probably easy to write an Ada 
library, exporting its functionality via "convention C", and then access 
it in Lua... 

I have not done this, but I have imported C into Ada, and exported Ada 
functionality into a (C++) program. It's reasonably easy (the C/C++ main 
needs to call adainit and adafinal functions) but some messing with 
makefiles is involved to tie them together.

You would probably need a minimal C wrapper to call adainit and adafinal 
functions, accessible from Lua. (Or if you can start the Lua code from a 
C main, it may be as easy to start it from Ada instead). But no messing 
about inside the compiler should be needed.

> If GNAT had a clearer separation of concerns between C and Ada, I could
> do the same with Ada or use Ada libraries when I want to but right now a
> lot seems to be bundled together and it is hard to tell what is binding
> and what is not.

I think the lack of separation may work FOR you in the above case...

- Brian