Re: ADA Popularity Discussion Request

[jayessay <nospam@foo.com>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On 08 Sep 2004 12:26:54 -0400, jayessay wrote:
> 
> > "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> > 
> >> The philosophy behind is that types are random artifacts of the
> >> program,
> > 
> > No, this is also incorrect.  The real difference is that with dynamic
> > typing _values_ have types _not_ variables.  Since _variables_ don't
> > even exist at runtime, your type information is largely gone at
> > runtime in static systems.
> 
> I suppose you are talking about polymorphic objects.

No, I'm not.  Simply put variable don't exist at runtime.  I'm talking
about every value having its type with it.


> 1. That statically typed languages cannot express polymorphism? This is
> plainly wrong.

This is irrelevant as again, the type information is basically gone.
You have certain limited RTTI abilities, but that is not the same.


> 2. That all polymorphic values should be considered of same type ANY? This
> is also wrong.

No, this is irrelevant.


> As Unchecked_Conversion does.

I guess i've forgotten this (never really used it much).  So, when
13.9(5) says an instance of this returns a value whose "representation
is the same as that of the source, how is that functionally different
from a cast?  I realize that can make a differnce at compile time, but
where's the runtime difference?  Especially as there's no type at
runtime.


> is a part of the language, why the compiler should be prevented from
> checking where it can?

It's _not_ prevented - it isn't _required_ to!


> Again, having accepted types you cannot argue that to check them earlier is
> worse than to check them later.

If you think I'm arguing that, you really haven't understood.  I'm not
saying checking them "earlier" is somehow bad, I'm saying it is
largely irrelevant in practice with dynamic typing because any type
inconsistency is caught during development anyway!


/Jon

-- 
'j' - a n t h o n y at romeo/charley/november com