Alternative object comprehension syntax

[marcelocantos]

for [k, v] in o is pretty cool but I was thinking it would be even nicer to have for k: v in o, which then allows for k:: v in o to iterate over hidden fields and for k::: v in o to hit all fields.

I'm happy to have a crack at it if you like the idea but it’s not a priority.

Notes:

1. Perhaps for [k]: v in o is better, since k is a variable, not a literal field name.
2. This syntax might allow order-preservation via for k: v preserve_order in {b: 1, a: 2}.

[CertainLach]

The [k, v] syntax is not something special made for object comprehension, this is a object deconstruction syntax, which is available in other contexts, i.e

local [a, b] = [1, 2];

The only thing added to comprehension is a semantic change, which allowed iteration over objects, which yields [key, value] pairs, I'm not sure how I feel about adding special syntax just for that, even if it does allow to implement order preservation here.