syntax for case ranges

kdex kdex at kdex.de
Mon Feb 3 17:58:37 UTC 2020


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
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