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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Ada and Unicode
Date: Mon, 19 Apr 2021 15:31:28 +0200	[thread overview]
Message-ID: <s5k0ne$opv$1@gioia.aioe.org> (raw)
In-Reply-To: s5jvp3$9kf$1@gioia.aioe.org

On 2021-04-19 15:15, Luke A. Guest wrote:
> On 19/04/2021 14:10, Dmitry A. Kazakov wrote:
> 
>>> They're different types and should be incompatible, because, well, 
>> they are. What does Ada have that allows for this that other languages 
>> doesn't? Oh yeah! Types!
>>
>> They are subtypes, differently constrained, like Positive and Integer. 
> 
> No they're not. They're subtypes only and therefore compatible. The UTF 
> string isn't constrained in any other ways.

Of course it is. There could be string encodings that have no Unicode 
counterparts and thus missing in UTF-8/16.

>> Operations are same values are differently constrained. It does not 
>> make sense to consider ASCII 'a', Latin-1 'a', UTF-8 'a' different. It 
>> is same glyph differently encoded. Encoding is a representation 
>> aspect, ergo out of the interface!
> 
> As I already said in Unicode the glyph is not part part of Unicode. The 
> single code point character concept doesn't exist anymore.

It does not matter from practical point of view. Some Unicode's 
idiosyncrasies are better ignored.

>> BTW, subtype is a type.

> subtype is a compatible type.

Ada subtype is both a sub- and supertype, i.e. substitutable [or so the 
compiler thinks] in both directions. A derived tagged type is 
substitutable in only one direction.

Neither is fully "compatible", because otherwise there would be no 
reason to have an exactly same thing.

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

  reply	other threads:[~2021-04-19 13:31 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-17 22:03 Ada and Unicode DrPi
2021-04-18  0:02 ` Luke A. Guest
2021-04-19  9:09   ` DrPi
2021-04-19  8:29 ` Maxim Reznik
2021-04-19  9:28   ` DrPi
2021-04-19 13:50     ` Maxim Reznik
2021-04-19 15:51       ` DrPi
2021-04-19 11:15   ` Simon Wright
2021-04-19 11:50     ` Luke A. Guest
2021-04-19 15:53     ` DrPi
2022-04-03 19:20     ` Thomas
2022-04-04  6:10       ` Vadim Godunko
2022-04-04 14:19         ` Simon Wright
2022-04-04 15:11           ` Simon Wright
2022-04-05  7:59           ` Vadim Godunko
2022-04-08  9:01             ` Simon Wright
2023-03-30 23:35         ` Thomas
2022-04-04 14:33       ` Simon Wright
2021-04-19  9:08 ` Stephen Leake
2021-04-19  9:34   ` Dmitry A. Kazakov
2021-04-19 11:56   ` Luke A. Guest
2021-04-19 12:13     ` Luke A. Guest
2021-04-19 15:48       ` DrPi
2021-04-19 12:52     ` Dmitry A. Kazakov
2021-04-19 13:00       ` Luke A. Guest
2021-04-19 13:10         ` Dmitry A. Kazakov
2021-04-19 13:15           ` Luke A. Guest
2021-04-19 13:31             ` Dmitry A. Kazakov [this message]
2022-04-03 17:24               ` Thomas
2021-04-19 13:24         ` J-P. Rosen
2021-04-20 19:13           ` Randy Brukardt
2022-04-03 18:04           ` Thomas
2022-04-06 18:57             ` J-P. Rosen
2022-04-07  1:30               ` Randy Brukardt
2022-04-08  8:56                 ` Simon Wright
2022-04-08  9:26                   ` Dmitry A. Kazakov
2022-04-08 19:19                     ` Simon Wright
2022-04-08 19:45                       ` Dmitry A. Kazakov
2022-04-09  4:05                         ` Randy Brukardt
2022-04-09  7:43                           ` Simon Wright
2022-04-09 10:27                           ` DrPi
2022-04-09 16:46                             ` Dennis Lee Bieber
2022-04-09 18:59                               ` DrPi
2022-04-10  5:58                             ` Vadim Godunko
2022-04-10 18:59                               ` DrPi
2022-04-12  6:13                               ` Randy Brukardt
2021-04-19 16:07         ` DrPi
2021-04-20 19:06         ` Randy Brukardt
2022-04-03 18:37           ` Thomas
2022-04-04 23:52             ` Randy Brukardt
2023-03-31  3:06               ` Thomas
2023-04-01 10:18                 ` Randy Brukardt
2021-04-19 16:14   ` DrPi
2021-04-19 17:12     ` Björn Lundin
2021-04-19 19:44       ` DrPi
2022-04-16  2:32   ` Thomas
2021-04-19 13:18 ` Vadim Godunko
2022-04-03 16:51   ` Thomas
2023-04-04  0:02     ` Thomas
2021-04-19 22:40 ` Shark8
2021-04-20 15:05   ` Simon Wright
2021-04-20 19:17     ` Randy Brukardt
2021-04-20 20:04       ` Simon Wright
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