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Re: Why is there no `until' in elisp?
From: |
Garreau\, Alexandre |
Subject: |
Re: Why is there no `until' in elisp? |
Date: |
Fri, 19 Oct 2018 20:08:07 +0200 |
User-agent: |
Gnus (5.13), GNU Emacs 25.1.1 (i686-pc-linux-gnu) |
On 2018-10-19 at 11:34, Stefan Monnier wrote:
>> think `until' should refer to the version I gave because this is
>> probably the one which is going to be implemented naively by most
>> people,
>
> BTW, this is only true if those people have to implement it on top of
> the pre-existing `while`. Once you go down to implementing it as
> a sequence of byte-codes, then the `until` you proposed is no simpler
> than the one I proposed.
>
> So reversing your argument, if Elisp had my `until` and you wanted to
> define `while` would you define it to return nil or to return t?
> IOW would you define it as
>
> (defmacro while (test &rest body)
> `(until (not ,test) ,@body))
> or
> (defmacro while (test &rest body)
> `(progn (until (not ,test) ,@body) nil))
>
> ?
The former, you’re right. What I was saying was mainly to keep
consistence, only then I was finding that, for me, returning the body of
a loop looks more logical than returning its condition (as you said,
this only makes sense for until). But now I saw the working of `while'
match the semantics you gave, I believe your version is better to be
implemented, in elisp.
- Re: Why is there no `until' in elisp?, (continued)
Re: Why is there no `until' in elisp?, Stefan Monnier, 2018/10/19
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 <=
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, 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?, Paul Eggert, 2018/10/17
- Re: Why is there no `until' in elisp?, Garreau\, Alexandre, 2018/10/17