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From: Roman Perepelitsa <roman.perepelitsa@gmail.com>
Date: Sat, 9 Nov 2019 09:52:27 +0100
Message-ID: <CAN=4vMriuV_u+LpOJDjRLtrE94h5hEXgrQXtVH-cpBg+kRCh-w@mail.gmail.com>
Subject: Re: What's the reasoning behind z & s returning nular for empty input?
To: Sebastian Gniazdowski <sgniazdowski@gmail.com>
Cc: Zsh Users <zsh-users@zsh.org>
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On Sat, Nov 9, 2019 at 9:40 AM Sebastian Gniazdowski
<sgniazdowski@gmail.com> wrote:
>
> On Sat, 9 Nov 2019 at 09:22, Roman Perepelitsa
> <roman.perepelitsa@gmail.com> wrote:
> >
> > On Sat, Nov 9, 2019 at 9:11 AM Sebastian Gniazdowski
> > <sgniazdowski@gmail.com> wrote:
> > > Thanks for the analysis. The additional problem is that quoted but
> > > @-lacking s-flag should still elide the empty elements, as the manual
> > > states. So this is an intentional exception and I wonder why it has
> > > been added?
> >
> > Here's the passage from zshexpn:
>
> Yes, I was also referring to this fragment, however it states that the
> empty elements should be removed, and even =E2=80=93 that they should be
> removed more eagerly, so I still wonder why produce a nular for an
> empty input?

Oh, I see what you mean. Apparently, only inner empty elements are
dropped by "${(s...)...}" while the first and the last are retained.

    "${(s:,:):-a,,b}" =3D> (a b)
    "${(s:,:):-,,}" =3D> ('' '')

Looks like it's either a bug in the code or in the documentation.

Roman.