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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Community Input for the Maintenance and Revision of the Ada
 Programming Language
Date: Mon, 2 Oct 2017 18:38:01 +0200
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Xref: news.eternal-september.org comp.lang.ada:48278
Date: 2017-10-02T18:38:01+02:00
List-Id: <comp.lang.ada>

On 2017-10-02 18:23, reinert wrote:
> On Monday, October 2, 2017 at 5:02:16 PM UTC+2, G.B. wrote:
> ......
>>
>>       14.     if Clock in t1 .. t2 then         -- this dows *not* function
>>                              |
>>           >>> scalar type required for range
>>
>> This does not work because Time is not a scalar type, even though
>> time per se, if measured in seconds, say, can make one think it is
>> of a scalar type. But type Time is private, in Ada, an abstract
>> point in time, not a number of time units.
> 
> I thought "x in a..b" was (should be?) short for "a <= x and x <= b"
> (where x, a and b are elements in a (strict) linearly ordered set or so).

Yes, but there is no Time interval type defined in Ada, alas. t1..t2 is 
an expression resulting in an interval.

The right way, considering that Clock is not constant, is:

    Clock - t1 in 0..t2 - t1 then

or, considering implied semantics, simply

    if Clock <= Deadline then

or

    if Clock - Started_At <= Timeout then

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