Re: Why is there no `until' in elisp?

[Garreau\, Alexandre]

On 2018-10-17 at 15:33, Paul Eggert wrote:
> On 10/17/18 2:49 PM, Garreau, Alexandre wrote:
>> Le 17/10/2018 à 14h35, Paul Eggert a écrit :
>>> On 10/17/18 2:15 PM, Garreau, Alexandre wrote:
>>>> “while” as used in natural language does *not* mean the same thing
>>> […] And the same is true for "until".
>> How’s that?
>
> In English, "until Y do X" typically means "keep checking Y while
> you're doing X and stop the instant that Y becomes true". This means
> something different from the proposed (until Y X), for the same reason
> that the common meaning of "while Y do X" in English means something
> different from (while Y X).

Really?  I thought it meant the same as “do X until Y” or “do X and stop
doing X when Y is true”, which to me seems the same.

While “while” seems to me to have some notion of contemporarity of the
two actions / expressions / etc., so it feels different to me, but
eventually I am to believe you.

>> I find “until” be a lot more used in all the languages I
>> know, including english.
>
> Although that might be true in other languages, it's certainly not
> true of English. Google, for example, reports about 8 billion hits for
> "while" but only 2 billion for "until". Admittedly Google hit counts
> are only vaguely approximate, but still....

Okay, you convinced me now (I get 6M and 2M).

>> The most obvious and only implementation of `unless', I ever seen *until
>> now* is (while (not cond) body)
>
> "unless" is something different from "until".

My bad, I made a mistake: I wanted to say `until' (as could show the
following expression).