Re: unsigned type

[anon@anon.org (anon)]

Read RM 3.5  ( 4 )

Is "A ( 0 .. 0 )" an example of null range.  By the definition in RM 3.5 
( 4 ), the Right side range (index) must be less than the Left side, so 
"A ( 0.. 0 )" is not a valid null range statement. So, this statement 
should generate a compiler or runtime error, because either range is not 
a subset of the range for Strings.


Reference:  RM 3.5 Scalar Types 

4   A range has a lower bound and an upper bound and specifies a subset of
the values of some scalar type (the type of the range).  A range with lower
bound L and upper bound R is described by ``L .. R''.  If R is less than L,
                                                       ^^^^^^^^^^^^^^^^^^^^
then the range is a null range, and specifies an empty set of values.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Otherwise, the range specifies the values of the type from the lower bound to
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
the upper bound, inclusive.  A value belongs to a range if it is of the type
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
of the range, and is in the subset of values specified by the range.  A value
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
satisfies a range constraint if it belongs to the associated range.  One
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
range is included in another if all values that belong to the first range
also belong to the second.



In <d8789140-eb5e-4f1d-b5ad-65df3db609cf@s6g2000vbp.googlegroups.com>, Adam Beneschan <adam@irvine.com> writes:
>On Jun 30, 8:59=A0am, Albrecht K=E4fer <albrecht_kae...@yahoo.de> wrote:
>> Adam Beneschan schrieb:
>>
>> >> So it is not a bug, it doesn't prove that the index is natural, it's
>> >> just the intended behaviour, designed in a way that makes user's life
>> >> easier - at the cost of compiler writers' life.
>>
>> > As a compiler writer, PLEASE TELL ME YOU DIDN'T MEAN THAT LAST PART
>> > LITERALLY!!!!!!!
>>
>> From what I gathered, this seems to be an important part of the Ada
>> philosophy.
>
>It's an important part of the Ada philosophy that working on writing
>an Ada compiler will cost you your life?
>
>> Probably the best example is tasking.
>
>OK, maybe that *is* a good example.  I've worked on tasking.... But
>I'm not quite dead yet, and I might still be able to pull through.
>(Depending on what changes the ARG may make to 3.10.2...)
>
>                                -- Adam
>