Re: Real syntax problems in Ada

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

On Wed, 29 Aug 2012 00:18:39 +0400, Vasiliy Molostov wrote:

> Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> яПНяПНяПНяПНяПН(яПН) яПН яПНяПНяПНяПНяПН яПНяПНяПНяПНяПНяПН Tue,  
> 28 Aug 2012 19:23:42 +0400:
> 
>> a symmetric declaration of a procedure would be:
>>
>>    X : procedure :=
>>       begin
>>          ...
>>       end X;
> 
> mnmn. where to apply parameter list declaration (suppose this as procedure  
> type "constraint")?
> 
> instead of subprogram access types we have objects in itself, how to  
> operate them? and ":=" is a re-definable construct, as I remember, while  
> we can not express operations on sub-program body. How about to implement  
> simple "<", ">" for sub-program bodies? hehe.

Bodies are not ordered. But if an order were required, e.g. to have
containers, ordered sets of, address could be used for that.

There is an important operation on bodies: composition:

   type Float_Valued is function (X : Float) return Float;
   X : Float_Valued := begin ... end;
   Y : Float_Valued := begin ... end;
   Z : Float_Valued := Y * X;

Another operation is inheritance. That is when one body operates T another
S and S <: T, inheritance is the body of T composed with type conversion S
to T.

And of course, parametrization, AKA instantiation of a generic body. Simple
non-generic form could deploy discriminants. That would give
specialization:

   type Integrator (Method : ...) is
      function (X : Float; ...) return Float;

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