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From: G. B. <nonlegitur@nmhp.invalid>
Newsgroups: comp.lang.ada
Subject: Re: stopping a loop iteration without exiting it
Date: Fri, 12 Jan 2018 09:22:43 -0000 (UTC)
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Date: 2018-01-12T09:22:43+00:00
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Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
> On 11/01/2018 21:54, G. B. wrote:
>> Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
>> 
>>>>> I have no idea what this is supposed to mean.
>>>> 
>>>> 
>>>> L:
>>>> [for|while...] loop
>>>> ...
>>>> goto L;
>>>> ...
>>>> end loop L;

>> loop is intended for the opposite, for when it’s not over yet.
>> For when it’s done again. “exit” cannot mean that, but the
>> hypothesized goto can.
> 
> 1. "exit" can:
> 
>    exit when <condition>;
> 
> When condition evaluates false the loop continues.
 
Well, no, the loop’s body continues. Doing so, it doesn’t
trigger another iteration, unlike “goto Continue”, or “goto L”.
It doesn’t drive.

Hence the following doesn’t apply to the case in point:
> 2. "goto" cannot in any deeper sense than "exit" does because it is not 
> "goto" which would drive the loop in this case.

>> Actually, “if” itself cannot directly make the program
>> iterate, unlike “goto”.
> 
> Not in the case at hand.

I’ll let your new case rest in your hands.


> P.S. Take if + a subroutine call. That gives recursion. Then following 
> your flawed logic either if or loop is bad.

Indeed this is a functionist’s main tenet. 
But then, if CALL and COND do not suffice, i.e., if they need 
an additional goto-like evaluation driver, then the functional
language is broken.