[spec] hex-escape punctuators

[ljharb]

Fixes #65

[michaelficarra]

Suggested change

	<dd>If the code unit represents a RegExp punctuator that needs escaping, or ASCII whitespace, it produces the code units for *"\x"* followed by the relevant escape code. If the code unit represents non-ASCII white space, it produces the code units for *"\u"* followed by the relevant escape code. Otherwise, it returns a List containing the original code unit.</dd>
	<dd>If _c_ represents a RegExp punctuator that needs escaping or ASCII whitespace, it produces the code points for *"\x"* followed by the relevant escape code. If _c_ represents non-ASCII white space, it produces the code points for *"\u"* followed by the relevant escape code. Otherwise, it returns a singleton List containing _c_.</dd>

[ljharb]

The _c_ replacements seem good, done; but i think the comma is necessary for it to read properly, and what is a "singleton" List vs any other kind of List?

[michaelficarra]

A singleton list has one element. This is to be explicit that it's not any old list that contains c (and possibly other things) but the list that contains only c.

[ljharb]

That's a really confusing word to use to me; in JS a singleton is when you have a class with a single shared instance. Is that qualifier necessary, given that it already says "a List containing c"?

[michaelficarra]

It's not necessary, I just thought it was a cheap way to be more precise. https://en.wikipedia.org/wiki/Singleton_(mathematics)

[ljharb]

I don't see how it adds precision, since the prose already explicitly says it has one item in it.

[michaelficarra]

Where does it say that?

[ljharb]

isn't "Otherwise, it returns a List containing the original code unit" that?

either way i'd like to land this, and i'm happy to have a PR tweaking it further, or we can do it at 262 time.

[michaelficarra]

isn't "Otherwise, it returns a List containing the original code unit" that?

I still don't know where this prose you're referring to is.

[a] is a list containing a, and is also a singleton list containing a. [a, b] is another list containing a, but is not a singleton list.

Anyway, it's not important, but for me it seemed like an easy win for precision.

[michaelficarra]

LGTM otherwise.