Generics and selection based on type

[Maciej Sobczak <no.spam@no.spam.com>]

Hi,

I would like to write a generic function that returns the string 
representation of its parameter, which can be a number or a string.
The sketch is:

generic
   type T is ...
function To_String(X : T) return String;

I want to use it this way:

function Int_To_String is new To_String(Integer);
function Positive_To_String is new To_String(Positive);
function Float_To_String is new To_String(Float);
function Identity is new To_String(String);

So that:

Int_To_String(7) = "7";
Positive_To_String(5) = "5";
Float_To_String(3.14) = "3.14";
Identity("Hello") = "Hello";

For this, it would be good to be able to select the implementation of 
To_String based on what the type is. If it's numeric - the 'Image 
attribute can be used. If it's already String - just return the 
argument. And so on.

Is it possible?

-- 
Maciej Sobczak : http://www.msobczak.com/
Programming    : http://www.msobczak.com/prog/