TC39 Delegates
2023-07-28
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21:51
<bakkot>
proposal to add observables: https://twitter.com/domfarolino/status/1684921351004430336
21:51
<bakkot>
specifically to add them to HTML, instead of JS
21:51
<bakkot>
for... reasons
21:52
<ljharb>
reasons that are unclear; i've recommended it be brought back to tc39 on the repo
21:52
<bakkot>
well, I mean
21:53
<bakkot>
the reason is almost certainly that he thinks it is not going to get through tc39 in any reasonable timeframe, and wants it in the platform, so he is routing around tc39
22:09
<snek>
is there anything in the js spec that would use observables
22:10
<snek>
we really need a more robust standard library
22:10
<snek>
i guess Atomics.waitAsync is the only thing that is ilke an "event"
22:34
<bakkot>
we really really need a more robust standard library yes
23:04
<TabAtkins>
Yeah, the "just do it in DOM" is almost certainly an "avoid the tc39 logjam which is extremely likely to result" thing. Plus as @snek said, DOM has a use-case immediately (event listeners), while JS itself doesn't.
23:08
<Kris Kowal>

My 2¢ is that ES already implies the shape of an Observable in the form of sync generator functions (dual to their use as iterators) and that we may as well make it official.

Observable {
  next(value: T) => void;
  return(value: T) => void;
  throw(error: unknown) => void;
}
23:10
<Kris Kowal>
Once @bakkot’s iterator helpers settle, there’ll be plenty of precedents on which to triangulate.
23:18
<bakkot>
(Michael Ficarra's and Yulia's iterator helpers, strictly speaking; I just helped out)
23:18
<bakkot>
also iterator helpers have settled and are shipping in Chrome (unstable - stable on Sep 12)
23:18
<bakkot>
though we'll want to add some more stuff
23:18
<Rob Palmer>

Bradley suggests there may be a performance advantage of implementing this at a higher level.

https://twitter.com/bradleymeck/status/1685008883385839616

23:19
<bakkot>
or at least I will
23:19
<bakkot>
(the observable proposal linked above does indeed draw on iterator helpers for its combinators)
23:34
<snek>

My 2¢ is that ES already implies the shape of an Observable in the form of sync generator functions (dual to their use as iterators) and that we may as well make it official.

Observable {
  next(value: T) => void;
  return(value: T) => void;
  throw(error: unknown) => void;
}
isn't the point of observables that they're push instead of pull? so no next/return/throw methods
23:35
<Kris Kowal>
Those are in fact push methods if you look closely.
23:35
<snek>
oh i see
23:35
<snek>
lol
23:37
<Kris Kowal>
I wrote a thing about this about nine years ago. https://github.com/kriskowal/gtor
23:37
<snek>
oh you wrote that
23:37
<snek>
small world as always
23:40
<Kris Kowal>
I do intend to dust it off some day since async iterators actually exist now.