From: Shark8 <onewingedshark@gmail.com>
Subject: Re: array from static predicate on enumerated type
Date: Thu, 18 Mar 2021 07:25:00 -0700 (PDT) [thread overview]
Message-ID: <5b078796-0976-4303-a733-3eaa66637b07n@googlegroups.com> (raw)
In-Reply-To: <7e1f3203-0fe9-428e-a8ac-411f432dca49n@googlegroups.com>
On Wednesday, March 17, 2021 at 7:04:06 PM UTC-6, Matt Borchers wrote:
> What I would expect is that P(12) would be an illegal access because 12 is not a valid value of Primes thus cannot be an index and a constraint error or out-of-range error would be thrown.
Which is reasonable.
> Wouldn't this just involve the compiler to insert "if x not in primes then raise..." if constraint checking is enabled?
Possibly, there are also dynamic-predicates to consider; imagine a subtype wherein the usage of some number excludes that number from the subtype. Maybe a "unused_room_keys" subtype for a hotel.
> Otherwise you have an erroneous program. Similarly, Primes'Succ(12) is also illegal. Primes'Pred(2) also illegal because there is no prime before 2 so presumably you have defined your Static_Predicate to enumerate the primes with 2 listed first.
Why?
Given the standard "subtype Natural is Integer range 0..Integer'Last" and "subtype Positive is Natural range Natural'Succ(Natural'First)..Natural'Last"
Positive'Pred( 1 ) = 0, and no CONSTRAINT_ERROR.
Do you want to break standard Ada usage?
next prev parent reply other threads:[~2021-03-18 14:25 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 20:49 array from static predicate on enumerated type Matt Borchers
2021-03-12 21:22 ` Egil H H
2021-03-12 22:16 ` Jeffrey R. Carter
2021-03-12 22:41 ` Dmitry A. Kazakov
2021-03-13 2:06 ` Matt Borchers
2021-03-13 4:55 ` Randy Brukardt
2021-03-15 14:16 ` Matt Borchers
2021-03-15 17:53 ` Shark8
2021-03-16 6:58 ` Randy Brukardt
2021-03-13 8:04 ` Dmitry A. Kazakov
2021-03-15 14:11 ` Matt Borchers
2021-03-15 17:48 ` Shark8
2021-03-15 20:25 ` Dmitry A. Kazakov
2021-03-16 13:27 ` Shark8
2021-03-16 14:25 ` Dmitry A. Kazakov
2021-03-17 4:05 ` Matt Borchers
2021-03-17 7:08 ` Dmitry A. Kazakov
2021-03-17 18:44 ` Matt Borchers
2021-03-17 19:41 ` Dmitry A. Kazakov
2021-03-18 1:30 ` Matt Borchers
2021-03-18 8:20 ` Dmitry A. Kazakov
2021-03-19 0:10 ` Matt Borchers
2021-03-19 8:00 ` Dmitry A. Kazakov
2021-03-18 10:15 ` Niklas Holsti
2021-03-18 10:47 ` AdaMagica
2021-03-18 11:26 ` Dmitry A. Kazakov
2021-03-19 0:34 ` Matt Borchers
2021-03-19 0:49 ` Jeffrey R. Carter
2021-03-23 1:07 ` Matt Borchers
2021-03-23 3:43 ` Randy Brukardt
2021-03-22 19:09 ` Niklas Holsti
2021-03-17 15:08 ` Shark8
2021-03-17 19:08 ` Matt Borchers
2021-03-17 20:41 ` Shark8
2021-03-18 1:04 ` Matt Borchers
2021-03-18 14:25 ` Shark8 [this message]
2021-03-18 23:36 ` Matt Borchers
2022-03-16 0:38 ` Thomas
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