"Yannick Duch�ne (Hibou57)" <yannick_duchene@yahoo.fr> wrote in message 
news:op.wfrdhbh1ule2fv@douda-yannick...
>Le Mon, 11 Jun 2012 20:29:47 +0200, Adam Beneschan <adam@irvine.com> a 
>�crit:
>> IIRC, some people have proposed adding unsigned integer types to the 
>> language; they've argued that modular types aren't good enough for some 
>> purposes.  But the idea was turned down.
>
>Why?

Why was it turned down? To much complication for to little gain, I think. 
There is a lot of overhead to having a new kind of type in the language (not 
only the type declaration, but also with generic formals, in Text_IO, etc.).

Janus/Ada has always supported unsigned representations of "signed" integer 
types (we did that in Ada 83, before there were modular types). I think most 
compilers do that, in fact. But as Adam says, you can force the signed 
representation in some cases, so for:

    type T is range 0 .. 2**32-1;

you have to support a signed version, which is easy to get -- just use 
T'Base. And for the largest integer representation supported by the compiler 
(32 or 64 or whatever), that's impossible, so Janus/Ada has to reject the 
above declaration. (We don't have general 64-bit integer support.)

                                                Randy.