Re: Ada noob here! Is Ada widely used?

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Sun, 06 Jun 2010 11:22:07 +0200, Dmitry A. Kazakov  
<mailbox@dmitry-kazakov.de> a écrit:
> But if you force yourself to instantiate earlier, you get a very fragile
Don't see a reason why ; and this even seems contradictory to me: the  
earlier you instantiate, the less complex it is. Or not ?

> design. Generics are against good design.
Suppose that is true, then this suggest to choose to use generic is a bad  
design choice. An example objection could be, when a generic is used,  
other ways may have been evaluated and excluded for some reasons. Or is  
Ada missing something so that people don't have any other choice than  
generic (generic as a fall-back) ? What could this other paradigm could  
looks like then ? (George would be interested in this I suppose)

In the area of other choices, would automatic generation or simply copy be  
a better choice (as this is one of the cases generics avoid) ? I feel it  
would be even less usable.

Your comments suggest this interesting question about what could be  
alternatives to generics.

> Add here that generics are non-testable. You can test instances, you
> cannot generics. Then Ada has been drifting towards C++ in the sense
> what promises gives you a successful compilation of the generic
> body, little, very little, nothing...
(another matter this one)
This is not like if generics could be instantiated with anything.  
Actually, this is not: you can require a formal parameter to be a discrete  
type, to be derived from another type, etc. So some assertions can be made  
on the validity of a generic's logic and implementation. Perhaps you are  
requesting for more ways to constrain formal parameters ? (I would agree  
with you, unless SPARK already support generics, which I have still not  
tested so far).

Oops, I have implicitly replaced “testable” by “provable”, hope you don't  
mind.

-- 
There is even better than a pragma Assert: a SPARK --# check.
--# check C and WhoKnowWhat and YouKnowWho;
--# assert Ada;
--  i.e. forget about previous premises which leads to conclusion
--  and start with new conclusion as premise.