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From: =?ISO-8859-1?Q?Elias_Salom=E3o_Helou_Neto?= <eshneto@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Efficiency of code generated by Ada compilers
Date: Tue, 10 Aug 2010 07:03:13 -0700 (PDT)
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Date: 2010-08-10T07:03:13-07:00
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On Aug 10, 9:57=A0am, Yannick Duch=EAne (Hibou57)
<yannick_duch...@yahoo.fr> wrote:
> Le Tue, 10 Aug 2010 14:26:25 +0200, Phil Clayton =A0
> <phil.clay...@lineone.net> a =E9crit:
>
> > =A0 A(A'Length - I - 1)
>
> > (not valid Ada, of course.)
>
> A(A'Last - (I - A'First))
>
> > Perhaps "reverse" would be a better name for the operator "not" when
> > the modulus is not a power of two?
>
> Or "wrapped" ? But this would only make sens on an array instance basis, =
=A0
> not on type basis. If the array actual range is not the same as the index=
 =A0
> type range, it fails. So this could not be a type primitive (operator). =
=A0
> May be an array attribute ? A'From_Last ? A'Last_Based ?
>
> "reverse" is already there for loop statements. I feel this makes for sen=
s =A0
> for loop, as what is reverse, is not the array index: this is the =A0
> iteration which goes reversed order.
>
> --
> There is even better than a pragma Assert: a SPARK --# check.
> --# check C and WhoKnowWhat and YouKnowWho;
> --# assert Ada;
> -- =A0i.e. forget about previous premises which leads to conclusion
> -- =A0and start with new conclusion as premise.

It is a pity that this post became a technical discussion on array
indexing. A simple question that could be asked in a single line is:
can Ada access arrays without range checking? My algorithm needs not
wrapping, neither it needs range checking!

Please, try avoiding pointless discussions on wrapped/non-wrapped
types. Recall that I do not even know Ada's syntax, let alone its
sophisticated type system. Your discussion can only possibly confuse
me.

Elias.