Re: Generic procedures and their parameters

Maciej Sobczak <no.spam@xxxxxxxxxxx> writes:

But then, you would need to have even such fundamental things like
Integer belong to Ordered'Class. It's a shaky ground.

Why is that shaky? Integer IS ordered.

Regarding Array_Type being implied, it is not. You can have any number of
array types based on exactly same combination of index and element types.
These types will be different types:
type I is ...;
type E is ...;
type Array1 is array (I range <>) of E;
type Array2 is array (I range <>) of E;

The types Array1 and Array2 are distinct types.

And now I see. I'm still having troubles with the fact that
"granularity" of type system in Ada can be much smaller than what can be
achieved with structural differences only.

It's a good thing that Ada allows Array1 and Array2 above to be
different types. But sometimes, structural typing would be better. In
fact, Ada has moved a bit in that direction -- anonymous access types
use structural typing, more or less.

The next step would be getting "<" from the element type,
which would eliminate a need to have Sort generic.

No, I disagree. There is a place for generic subprograms, otherwise we'd
have everything in a single hierarchy with Object at the top. It's not a
coincidence that "other languages" drift towards supporting generics,
even if they already had such single-rooted hierarchies.

A hierarchy with Object at the top would be a Good Thing, IMHO. Trees
are more aesthetically pleasing than forests. But you're right that you
still need some sort of generic facility, so you can have strongly typed
containers. But I think perhaps we should have generic types
(i.e. parameterized types) rather than generic packages. That's what
discriminants do, but they're severely limited. It would make sense to
have a discriminant that is a type, so you could say:

My_Sequence: Sequence(Element => Integer) := (1, 2, 3);

- Bob
.

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