syntax for case ranges

Jordan Harband ljharb at gmail.com
Wed Feb 19 20:01:30 UTC 2020


@kdex (sorry i missed this; your message was in my spam folder) if you find
a way that Annex E is non-exhaustive, please file an issue on the spec - I
would like it to be exhaustive.

On Mon, Feb 3, 2020 at 11:16 AM Naveen Chawla <naveen.chwl at gmail.com> wrote:

> Thanks! Although I think it is a value judgement about how much risk is
> worth how much reward, and which reward, so I wouldn't classify it as
> necessarily a complete set of criteria yet, but it is certainly in the
> right direction. And very interesting to me. Thank you.
>
> On Tue, 4 Feb 2020 at 00:40, Mark S. Miller <erights at gmail.com> wrote:
>
>> While correct, each case asked the browser makers to make a risky and
>> costly bet. When the risk was low and the payoff high, they've been great
>> at doing so. This one does not fall into the viable risk vs reward
>> territory.
>>
>>
>> On Mon, Feb 3, 2020 at 7:58 AM kdex <kdex at kdex.de> wrote:
>>
>>> Yes, there have been numerous backwards-incompatible changes to the
>>> language
>>> over the years.
>>>
>>> You can find a list of them in section E of the ECMAScript language
>>> standard.
>>> IIRC, that list is non-exhaustive.
>>>
>>> On Monday, February 3, 2020 6:35:12 PM CET Naveen Chawla wrote:
>>> > Thank you Claude! I did miss the point.
>>> >
>>> > Have there ever been "BC" breaks introduced into the language before?
>>> If
>>> > so, is there a sustainable standard for an "acceptable" one?
>>> >
>>> > On Mon, 3 Feb 2020 at 22:47, 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
>>> > >>>>>>>
>>> > >>>>>>> }
>>> > >>>>>>>
>>> > >>>>>>>
>>> > >>>>>>> _______________________________________________
>>> > >>>>>>> es-discuss mailing
>>> > >>>>>>> listes-discuss at mozilla.orghttps://
>>> mail.mozilla.org/listinfo/es-disc
>>> > >>>>>>> uss
>>> > >>>>>>>
>>> > >>>>>>>
>>> > >>>>>>> _______________________________________________
>>> > >>>>>>> es-discuss mailing list
>>> > >>>>>>> es-discuss at mozilla.org
>>> > >>>>>>> https://mail.mozilla.org/listinfo/es-discuss
>>> > >>>>>>
>>> > >>>>>> _______________________________________________
>>> > >>>>>> es-discuss mailing list
>>> > >>>>>> es-discuss at mozilla.org
>>> > >>>>>> https://mail.mozilla.org/listinfo/es-discuss
>>> > >>>>>
>>> > >>>>> _______________________________________________
>>> > >>>>> es-discuss mailing list
>>> > >>>>> es-discuss at mozilla.org
>>> > >>>>> https://mail.mozilla.org/listinfo/es-discuss
>>> > >>>>
>>> > >>>> --
>>> > >>>> -----
>>> > >>>>
>>> > >>>> Isiah Meadows
>>> > >>>> contact at isiahmeadows.com
>>> > >>>> www.isiahmeadows.com
>>> > >>>> _______________________________________________
>>> > >>>> es-discuss mailing list
>>> > >>>> es-discuss at mozilla.org
>>> > >>>> https://mail.mozilla.org/listinfo/es-discuss
>>> > >>>
>>> > >>> _______________________________________________
>>> > >>> es-discuss mailing list
>>> > >>> es-discuss at mozilla.org
>>> > >>> https://mail.mozilla.org/listinfo/es-discuss
>>> > >>
>>> > >> --
>>> > >>
>>> > >>   Cheers,
>>> > >>   --MarkM
>>> > >
>>> > > _______________________________________________
>>> > > es-discuss mailing list
>>> > > es-discuss at mozilla.org
>>> > > https://mail.mozilla.org/listinfo/es-discuss
>>
>>
>>
>> --
>>   Cheers,
>>   --MarkM
>>
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