Re: Text_IO, was: Re: Something I don't understand

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

On Wed, 19 Feb 2014 17:01:45 -0500, Robert A Duff wrote:

> Niklas Holsti <niklas.holsti@tidorum.invalid> writes:
> 
>> No, dynamic type safety is not fully "Ada type safe". Ada is (mainly)
>> statically type safe; dynamism only enters in subtype safety.
> 
> Well, if you take the view that "types" are "those things that can be
> checked statically", then all programming languages are statically type
> safe, rendering the notion meaningless.  Even something like 'bash',
> which has only one (static) type.  In this view, 'bash' does zero static
> type checking, yet all the type checking it does is static.

Yes, there is no such thing as a truly untyped language because a type can
always be added afterwards. [However I wonder you supporting that kind
argument, for second time, actually, after you said (rightfully) that there
is written Ada and Reference Manual's Ada.]

The question is how much of the language semantics is mapped on the types,
explicit or implied no matter. That amount makes Ada strongly typed and
bash "untyped."

> In other words, the term "subtype" in Ada is a cheat, deliberately used
> to enable bogus claims about static type safety in Ada, as if the
> run-time checks associated with subtypes somehow don't count.

Yes, they do not count. Constraint_Error is not a failed check, it is a
contracted behavior.

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