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Date: Wed, 3 Oct 2018 18:25:52 +0200
From: Marc Chantreux <eiro@phear.org>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: Zsh Users <zsh-users@zsh.org>
Subject: Re: dangerous behavior of while in zsh 5.6 ?
Message-ID: <20181003162552.GA14697@prometheus.u-strasbg.fr>
References: <20181003143800.GA9162@prometheus.u-strasbg.fr>
 <CAH+w=7ZuFKDMBvL7XdSqYXcXy5hrc_zQPK0KsLrTZ1Szrfu6Ow@mail.gmail.com>
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User-Agent: Mutt/1.10.1 (2018-07-13)

hello Bart,

> >     while (( i-- ))
> >         print $i
> This is just a syntax error for me (or prints the PS2 prompt if
> interactive), so I'm not sure how you're getting it to do anything.

i have the same behavior when interactive but no syntax error otherwise.

instead:

    {   repeat 2 print $[i++]
        while (( i-- )) print $i
    } |sed 10 | xargs

    > 0 1 1 0

    {   repeat 2
            print $[i++]
        while (( i-- ))
            print $i
    } |sed 10q | xargs

    > 0 1 1 0 -1 -2 -3 -4 -5 -6

but thanks to your enlightening explainations, i understand what's going
on and now have a short, gorgeous way to write a forever loop.

    nat () {
        local -i x=${1-0}
        while print $[x++]
    }

thank you very much, Bart.

regards.
marc