July 29 2014 TC39 Meeting Notes

Brendan Eich brendan at mozilla.org
Fri Aug 8 12:06:58 PDT 2014

Hi Andy, I'm sorry for what looks to you like black-holing. I admit 
Rick's notes are terse but that shouldn't be taken for "brusque", and 
where they need supplementation, I try to post followups to es-discuss.

However, in this case I don't think the charge is fair to TC39 in full. 
I'm a long-time champion (probably erstwhile at this point) of 
generators, and I did reply to es-discuss about the history and 
rationale for forcing a return instead of using an exception.

I think Dave lacks time to keep up with es-discuss, but you can always 
reach out to him by email. Anyway, you don't need him here, you've heard 
from at least Allen and me on this list.


Andy Wingo wrote:
> Hi,
> I would like to register a gripe.  I have been unhappy with my
> interactions with TC39 since things started happening more in F2F
> meetings and private mails than online.  I wish that people would do
> things more on es-discuss.  As an example:
> On Tue 05 Aug 2014 18:30, Rick Waldron<waldron.rick at gmail.com>  writes:
>> >  ## Short discussion about making generator.return() throw a special
>> >  exception.
>> >
>> >  DH: Want to bring up Andy Wingo's preference (discussed on es-discuss)
>> >  for modeling return() as an exception rather than a return.
>> >
>> >  General opposition.
>> >
>> >  #### Conclusion/resolution
>> >
>> >  - keep as is: return() method produces a return control flow, not an
>> >  exception
> No reason, no response on the list to the salient points, no response
> from Dave Herman; too bad.
>> >  ## Yield *
>> >
>> >  AWB: Does an internal throw
>> >
>> >  When a `generator.throw()` is called and the generator has a yield* the
>> >  spec currently calls `throw` in the yield* expression
>> >
>> >  DH: Call return() on the outer generator, delegates calling return() to
>> >  the delegated `yield *`
> This kind of proposal is particularly egregious as a
> way-past-the-last-minute semantic change that was proposed only at a F2F
> meeting without any other possible input, even from generators
> "champions" (if I am that any more).  The discussion has people
> participating that never post on the list.
> Note that in this particular case the semantics of a return() are fully
> specified with the old agreed semantics if return() is implemented as an
> exception.
> Grumpily yours,
> Andy
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