Re: Ada generics

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 28 Dec 2006 08:29:15 -0800, Hyman Rosen wrote:

> Dmitry A. Kazakov wrote:
>> They reap what they sowed. Should Ada or C++ go into that mess?
> 
> Well, they have. It comes of being unwilling to say to the rest of the
> world that yes, this programming language is based on English, deal
> with it. I expect that one day we will get many alternative sets of
> keywords so that people can write "loop" and "type" and "generic" in
> their own language.

Yuck. Maybe it could turn an advantage for Ada being a niche language then.
I hope that a pressure to do that will not be high enough to carry out such
mess.

>> Huh, Ada.Numerics has pi and e...
> 
> I found this on the web:
>     package Ada.Numerics is
>     pragma Pure (Numerics);
>         Argument_Error : exception;
>         Pi : constant :=
> 3.14159_26535_89793_23846_26433_83279_50288_41971_69399_37511;
>         e : constant :=
> 2.71828_18284_59045_23536_02874_71352_66249_77572_47093_69996;
>     end Ada.Numerics;
> 
> Those look like rational numbers to me.

But they are not. If you are going to extend a language in this direction
you should introduce new numeric types, like rational /= float. Further
that does no solve the problem. Because float still exists. You cannot
define float as mathematical real, that would not be computable. You could
say (as it actually is), that float is an interval with rational bounds.
But then you would discover that intervals are incomparable (so the
empirical rule "never compare floats for equality.") This way or another,
it is cannot work.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de