TC39 General on 2022-10-26

18:25	<nicolo-ribaudo>	Why doesn't `reduce` take a `thisArg` parameter?
18:31	<bakkot>	presumably because it already has a different optional parameter?
20:00	<Kris Kowal>	Indeed, and `reduce` is arity sensitive so you can’t throw another optional argument after it.
20:01	<Kris Kowal>	`> [].reduce(() => {}) Uncaught TypeError: Reduce of empty array with no initial value at Array.reduce (<anonymous>) > [].reduce(() => {}, undefined) undefined`
20:04	<Kris Kowal>	In a parallel universe where Pepsi and Coke products coëxist in peace, the `basis` argument of `reduce` is required and `thisArg` is optional on the end.
20:05	<bakkot>	it would not make sense to make the `basis` required; there are plenty of things which support some add/join/whatever operation but which do not have an identity
20:08	<bakkot>	(assuming by `basis` you mean the initial value, anyway)
20:08	<Kris Kowal>	Yeah, as in `basis` and `recursive step`. `reduce` is induction with a funny name.
20:09	<Kris Kowal>	Could be worse. Like, `fold`.
20:09	<bakkot>	`fold` is at least physically evocative
20:10	<Kris Kowal>	I’m speaking from a place of caffeine. Please take all above in jest.
20:37	<nicolo-ribaudo>	Thanks to both of you!
20:38	<nicolo-ribaudo>	I have another "why?" 😄 Why do we need to disallow line terminators between `yield` and ``? Just for consistency with non-`` `yield`?
20:39	<bakkot>	my guess - again just a guess - is to preserve the possibility of `` as a prefix operator, as in `yield\nx`
20:40	<bakkot>	though actually that doesn't really make the situation better, come to think
20:40	<bakkot>	yeah I dunno
20:41	<nicolo-ribaudo>	That operator screams "ASI hazard" very loudly :P
20:42	<bakkot>	eh, so does `+`
20:42	<bakkot>	`+x === 1 && console.log('x is 1')`
20:42	<bakkot>	I guess probably don't write that code though