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Re: Why is there no `until' in elisp?
From: |
Yuri Khan |
Subject: |
Re: Why is there no `until' in elisp? |
Date: |
Wed, 17 Oct 2018 16:46:08 +0700 |
On Wed, Oct 17, 2018 at 4:23 PM Garreau, Alexandre
<address@hidden> wrote:
>
> Something such as the C “do” construct might overcomplicate the
> language, while I think normal `while' and `until' are not only simpler
> but also superior: with those you have the case of 0 loops, in which
> basically works as a when.
The post-condition loop enables the “at-least-once” case, which is
also occasionally useful, e.g.: Attempt an API call until it succeeds.
> > However, in many languages that have an ‘until’ loop as a language
> > construct, it is a post-condition loop. The body is executed first,
> > then the condition is evaluated.
>
> Which languages? I looked again in bash to be sure, and bash doesn’t do
> that.
+ Well, you mentioned the C ‘do’/‘while’, for one; it is a
continuation post-condition loop. C++, Java, PHP, Javascript and many
other languages inherited that.
+ Pascal has ‘repeat’/‘until’ (a termination post-condition loop), and
it was my first association for the name ‘until’.
− Bash’s ‘until’/‘do’/‘done’ is a termination pre-condition loop, you’re right.
+ In Perl, both ‘while’ (continuation) and ‘until’ (termination) can
be used as pre-conditions and post-conditions.
- Re: Why is there no `until' in elisp?, (continued)
- Re: Why is there no `until' in elisp?, Stefan Monnier, 2018/10/16
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/16
- Re: Why is there no `until' in elisp?, Stefan Monnier, 2018/10/16
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17
- Re: Why is there no `until' in elisp?, Stefan Monnier, 2018/10/17
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17
- Re: Why is there no `until' in elisp?, Stefan Monnier, 2018/10/19
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/19
Re: Why is there no `until' in elisp?, Yuri Khan, 2018/10/17
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17
- Re: Why is there no `until' in elisp?,
Yuri Khan <=
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17
- Re: Why is there no `until' in elisp?, Paul Eggert, 2018/10/17
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17
- Re: Why is there no `until' in elisp?, Paul Eggert, 2018/10/17
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17
- Re: Why is there no `until' in elisp?, Paul Eggert, 2018/10/17
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17
Re: Why is there no `until' in elisp?, Elias Mårtenson, 2018/10/17
Re: Why is there no `until' in elisp?, Stefan Monnier, 2018/10/17