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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Is this expected behavior or not
Date: Wed, 13 Mar 2013 18:34:35 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2013-03-13T18:34:35-04:00
List-Id: <comp.lang.ada>

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> Ada's design choice was in favor of Integer's order: 'Succ (3)=4. But
> user's expectation was the order from the problem space 'Succ(3)=5.

As a user, what is your expectation for the following?

    X : Prime := 3;

    A : Integer := Prime'Succ (X); -- A = 4
    B : Integer := Integer'Succ (X); -- B = 4
    C : Integer := X + 1; -- C = 4
    D : Prime := X + 1; -- Constraint_Error on the ":=", not on the "+"

    E : Integer := Positive'Pred(1); -- E = 0
    F : Integer := Positive'Pred(-100); -- F = -101

    type T is range 1..10;
    G : T := 10;
    H : T := 10;
    I : T := (G + H) / 2; -- I = 10

I've shown the actual Ada semantics in comments.
Does your expectation differ?

(Nitpick: The expression G+H could overflow, if the compiler
chose a base range for T of -10..10.  No compiler does that,
but if you're worried about it, you could declare
"type T is new Integer range 1..10" instead.)

- Bob