syntax for case ranges

Mark S. Miller erights at gmail.com
Mon Feb 3 19:09:59 UTC 2020


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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