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Re: Algol 68 - array of procedures aligned at index 0 ?

From antispam@fricas.org (Waldek Hebisch)
Newsgroups comp.lang.misc
Subject Re: Algol 68 - array of procedures aligned at index 0 ?
Date 2025-11-11 12:53 +0000
Organization To protect and to server
Message-ID <10evbjl$3m7uc$1@paganini.bofh.team> (permalink)
References (10 earlier) <10en6ch$2gh04$1@dont-email.me> <10eqi8u$336v1$2@paganini.bofh.team> <10eqv9n$3i5k8$1@dont-email.me> <10esqtj$3cbvm$2@paganini.bofh.team> <10etjab$96rq$2@dont-email.me>

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Lawrence D’Oliveiro <ldo@nz.invalid> wrote:
> On Mon, 10 Nov 2025 13:56:05 -0000 (UTC), Waldek Hebisch wrote:
> 
>> Lawrence D’Oliveiro <ldo@nz.invalid> wrote:
>>>
>>> On Sun, 9 Nov 2025 17:16:16 -0000 (UTC), Waldek Hebisch wrote:
>>>
>>>> But otherwise I am not aware of _useful_ Algol 68 features missing
>>>> from Extended Pascal.
>>>
>>> Dynamic declaration of array bounds? Slices? Checked unions?
>>
>> Extended Pascal has schema types.
> 
> I’m talking about something like, just a contrived example (untested
> code, hope any errors do not obscure my intent):
> 
>     procedure fred
>       (
>         data : array [low .. high : integer] of data_type
>       );
> 
>         var
>             temp : array [0 .. high - low] of other_data_type;
> 
>       begin
>         ...
>       end {fred};
> 
> Would that be legal?

Syntax is different.  You could use conformal array as an argument,
but consistenly using schemas you should write sometimg like this:

    type ar1d(low, high : integer) = array [low .. high] of data_type;
    procedure fred(data : ar1d);
        type ar1o(low, high : integer) = 
             array [low .. high] of other_data_type;
        var temp : ar1o(0, data.high - data.low);
        begin
            ...
        end;

That is you need type definition to define a schema.  You can use
schema without actual parameters (undiscriminated schema) as type
of function/procedure arguments and to declare pointer types.
Schema with actual parameters (discriminated schema) can be used
where other type are used.  Actual parameters can be variable.

>> Concerning checked unions, I am not sure what you mean here. Pascal
>> variant records may have selector field. Quality Pascal
>> implementation will check that field that you access is consistent
>> with the selector field, either by default or as a compiler option.
>> Pascal does not protect you from changing selector field in a way
>> which is inconsistent with stored values.
> 
> Algol 68 won’t allow you to access a variant that is inconsistent with
> the current selector field value. Access has to be done via a
> “conformity clause”, which looks like a CASE statement but keys off
> the current variant selection.
> 
> Also, the selector can only be updated by an assignment to the entire
> object, which sets a value for the right variant field at the same
> time.

OK.

-- 
                              Waldek Hebisch

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Thread

Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-01 16:00 +0100
  Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-01 20:54 +0000
    Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-02 07:33 +0100
      Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-02 09:50 +0100
      Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-02 11:10 +0000
        Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-02 11:44 +0000
          Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-02 13:12 +0100
            Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-02 13:23 +0100
          Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-03 00:42 +0000
            Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-03 15:03 +0000
              Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-03 16:40 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-03 17:00 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-03 21:02 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-03 20:34 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-03 22:35 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-03 23:37 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-04 07:16 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-04 11:10 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? David Brown <david.brown@hesbynett.no> - 2025-11-04 16:46 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-04 16:17 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-04 17:26 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? David Brown <david.brown@hesbynett.no> - 2025-11-04 17:49 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-04 18:38 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-04 19:30 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? David Brown <david.brown@hesbynett.no> - 2025-11-04 21:04 +0100
                Homebrew languages (was: Algol 68 - array of procedures aligned at index 0 ?) bart <bc@freeuk.com> - 2025-11-06 00:39 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-05 12:52 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-05 14:02 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-04 18:28 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? David Brown <david.brown@hesbynett.no> - 2025-11-04 21:14 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-03 17:32 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-03 20:28 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-03 20:10 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-03 22:31 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-04 12:24 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? David Brown <david.brown@hesbynett.no> - 2025-11-04 17:02 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-05 12:25 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-05 14:12 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-05 14:28 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-06 08:29 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-06 14:18 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-06 15:58 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-07 21:22 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-07 23:13 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-08 03:17 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? antispam@fricas.org (Waldek Hebisch) - 2025-11-08 03:50 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-08 04:47 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-08 12:42 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-08 21:37 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-09 20:34 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-09 21:08 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? antispam@fricas.org (Waldek Hebisch) - 2025-11-09 16:58 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-08 11:34 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? antispam@fricas.org (Waldek Hebisch) - 2025-11-09 17:16 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-09 19:11 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-09 20:58 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? antispam@fricas.org (Waldek Hebisch) - 2025-11-10 13:56 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-10 20:52 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? antispam@fricas.org (Waldek Hebisch) - 2025-11-11 12:53 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-11 20:51 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? David Brown <david.brown@hesbynett.no> - 2025-11-06 17:14 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-06 19:41 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-06 22:01 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-08 12:24 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-07 23:33 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-04 00:35 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-04 07:07 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-04 14:57 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-05 23:59 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-06 01:03 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-06 07:40 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-06 10:59 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-06 16:59 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-06 17:58 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-06 20:14 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-06 22:16 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-06 22:47 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-07 14:34 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-07 15:42 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-07 16:50 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-07 19:49 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-07 20:01 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-08 00:26 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-08 01:54 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-08 14:00 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-08 15:24 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-10 00:11 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-10 00:43 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? David Brown <david.brown@hesbynett.no> - 2025-11-10 09:08 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? antispam@fricas.org (Waldek Hebisch) - 2025-11-10 13:28 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? ram@zedat.fu-berlin.de (Stefan Ram) - 2025-11-10 10:11 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-10 11:02 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-10 15:00 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? antispam@fricas.org (Waldek Hebisch) - 2025-11-10 15:52 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-10 17:05 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-10 10:10 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? Andy Walker <anw@cuboid.co.uk> - 2025-11-10 15:48 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-07 17:59 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-07 18:39 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-12 11:01 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-12 20:47 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-12 22:22 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-12 23:28 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-13 01:31 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-11-13 09:35 +0100
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-13 11:37 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-04 01:05 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? bart <bc@freeuk.com> - 2025-11-04 01:24 +0000
                Re: Algol 68 - array of procedures aligned at index 0 ? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-04 02:28 +0000

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