From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Bug in Ada - Latin 1 is not a subset of UTF-8
Date: Tue, 18 Oct 2016 22:03:13 +0200
Date: 2016-10-18T22:03:13+02:00 [thread overview]
Message-ID: <nu5v60$1h81$1@gioia.aioe.org> (raw)
In-Reply-To: nu5mgi$7er$1@dont-email.me
On 2016-10-18 19:35, G.B. wrote:
> On 18.10.16 18:35, Dmitry A. Kazakov wrote:
>> No invariant can make Latin-1 A-umlaut UTF-8 A-umlaut.
>
> Who would ever want to do that?
Somebody claiming that UTF-8 string is a constrained subtype of Latin-1
string.
> To get a subset U from a set S, you apply a constraint
> to S. That's not (easily) expressible in Ada in this case.
There is no such constraint at all. A-umlaut in Latin-1 is one
character, in UTF-8 it is two characters.
To introduce a subtype relationship we need a conversion, not a
constraint. Ada does not support this method of subtype construction.
> But if it is, with the help of a predicate, the we can
> say that UTF_8_String is-a "constrained" String because
> their sets are.
They are not, as demonstrated on the example of A-umlaut.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2016-10-18 20:03 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-17 20:18 Bug in Ada - Latin 1 is not a subset of UTF-8 Lucretia
2016-10-17 20:57 ` Jacob Sparre Andersen
2016-10-18 5:44 ` J-P. Rosen
2016-10-17 23:25 ` G.B.
2016-10-18 7:41 ` Dmitry A. Kazakov
2016-10-18 8:23 ` G.B.
2016-10-18 8:45 ` Dmitry A. Kazakov
2016-10-18 10:09 ` G.B.
2016-10-18 12:24 ` Dmitry A. Kazakov
2016-10-18 15:10 ` G.B.
2016-10-18 16:35 ` Dmitry A. Kazakov
2016-10-18 17:35 ` G.B.
2016-10-18 20:03 ` Dmitry A. Kazakov [this message]
2016-10-19 8:15 ` G.B.
2016-10-19 8:25 ` G.B.
2016-10-19 8:49 ` Dmitry A. Kazakov
2016-10-19 14:20 ` G.B.
2016-10-19 16:20 ` Dmitry A. Kazakov
2016-10-20 0:31 ` Randy Brukardt
2016-10-20 7:36 ` Dmitry A. Kazakov
2016-10-21 12:28 ` G.B.
2016-10-21 16:13 ` Lucretia
2016-10-21 16:43 ` Dmitry A. Kazakov
2016-10-22 5:51 ` G.B.
2016-10-22 7:49 ` Dmitry A. Kazakov
2016-10-24 11:35 ` Luke A. Guest
2016-10-24 13:01 ` Dmitry A. Kazakov
2016-10-24 14:54 ` Luke A. Guest
2016-10-22 1:53 ` Randy Brukardt
2016-10-28 21:08 ` Shark8
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