Re: 'in' keyword today (was Re: mathlib)

[Coroutines <coroutines@...>]

Er, I know we've breached into the "tricks with the debug library"
space now, but I'd like to recap some important parts of the proposal:

Some of us would like to see this become part of Lua -- the expression
form: "a, b, c in some_table" being equivalent to "some_table.a,
some_table.b, some_table.c"

Which would enable this:

local tcat, tins, trem = concat, insert, remove in table

This short-form, syntactic sugar would be added as well for local declarations:

local concat, insert, remove in table

That last one would basically be the same as the hacky from() where it
looks for the nearest locals on the stack and reassigns them to match
the identifiers with identical keys in the table.