syntax for case ranges

Isiah Meadows contact at isiahmeadows.com
Mon Feb 3 17:22:46 UTC 2020


Does make me wonder if engines should start collecting statistics on how
often it's used and how often that result differs from if a Python-style
chained comparison was done instead.

On Mon, Feb 3, 2020 at 09:18 Claude Pache <claude.pache at gmail.com> wrote:

> Try typing `3 < 2 < 1` in the web console of your favourite browser, and
> see the result: it will evaluate to `true`. No, your browser isn’t buggy,
> it is just following blindly the semantics of `<`.
>
> Modifying the meaning of `3 < 2 < 1` in order to make it evaluating  to
> `false` is a BC break. Is it acceptable? Dunno.
>
> —Claude
>
> Le 3 févr. 2020 à 15:23, Naveen Chawla <naveen.chwl at gmail.com> a écrit :
>
> Hi!
>
> I didn't understand your reply.
>
> I think currently it would raise an error, because 1 < 2 < 3 is currently
> saying (probably) true < 3.
>
> But a "new" syntax could possibly parse that as a "chain" of comparisons.
>
> Would this be acceptable to introduce into JavaScript (just curious)?
>
> I've probably missed your point entirely, because I saw a short message "3
> < 2 < 1 //true", and I've assumed you meant it in reverse.
>
> On Sat, 1 Feb 2020 at 23:12, Mark S. Miller <erights at gmail.com> wrote:
>
>> 3 < 2 < 1;  // true
>>
>>
>> On Sat, Feb 1, 2020 at 3:03 AM Naveen Chawla <naveen.chwl at gmail.com>
>> wrote:
>>
>>> Certain languages allow the expression 0<x<5. Does anybody know if this
>>> would be syntactically possible in JavaScript? Of course this would only
>>> apply for "if"/"while" statements.
>>>
>>> On Fri, 31 Jan 2020 at 22:41, Isiah Meadows <contact at isiahmeadows.com>
>>> wrote:
>>>
>>>> Still better to discuss it there - it's highly related to your
>>>> suggestion. And I'm pretty sure an issue already exists related to that.
>>>>
>>>> On Fri, Jan 31, 2020 at 09:06 Sultan <thysultan at gmail.com> wrote:
>>>>
>>>>> The pattern matching proposal does not handles the mentioned case:
>>>>>
>>>>> switch(type) { case 0...5: } being the equivalent of switch(type) {
>>>>> case 0: case 1: case 2: case 3: case 4: case 5: }
>>>>>
>>>>> On Fri, Jan 31, 2020 at 7:36 PM Bruno Macabeus <
>>>>> bruno.macabeus at gmail.com> wrote:
>>>>>
>>>>>> I agree with Oriol.
>>>>>> We already have the proposal pattern matching, that has a very
>>>>>> similar effect.
>>>>>> I think that is better to improve pattern matching proposal in order
>>>>>> to be able to match using ranges (or at least check if it's good to do)
>>>>>> instead of create a new proposal.
>>>>>>
>>>>>> On Fri, 31 Jan 2020 at 14:08, Oriol _ <oriol-bugzilla at hotmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> This sounds like https://github.com/tc39/proposal-pattern-matching
>>>>>>>
>>>>>>> El 31/1/20 a les 10:57, Sultan ha escrit:
>>>>>>>
>>>>>>> For example, the following:
>>>>>>>
>>>>>>> switch (value) {
>>>>>>>     case 0...9: break
>>>>>>>     case 'a'...'z': break
>>>>>>> }
>>>>>>>
>>>>>>>
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>>>> --
>>>> -----
>>>>
>>>> Isiah Meadows
>>>> contact at isiahmeadows.com
>>>> www.isiahmeadows.com
>>>> _______________________________________________
>>>> es-discuss mailing list
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>>
>>
>> --
>>   Cheers,
>>   --MarkM
>>
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-- 
-----

Isiah Meadows
contact at isiahmeadows.com
www.isiahmeadows.com
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