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

[Paul Eggert <eggert@cs.ucla.edu>]

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).


>
> 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....


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

"unless" is something different from "until". Anyway, we're not making 
much progress here; feel free to have the last word.