i totally forgot about this interaction between 'float is the only number type' and 'string is the only key type'. at least sometimes the numbers are known-int
They added Map as a proper key-value data structure so it's a good idea to ban using objects as map data structure now, just like banning any usage of `var` (using only let/const) with "use strict" to prevent implicit usage of that nonsense broken form of scoping with hoisting.
Except it's not a proper key-value data structure, arrays and objects used as keys in one do the lookup via the use of the `==` operator. So it might work, until it doesn't because you got a key in from a different path and then nothing works.
I don't think it's reasonable to blame Map for objects implementing equality as reference equality. It would be worse if it deviated from the standard definition of equality in the language. Arrays and objects are what need to be fixed, not Map using `===` (it doesn't use `==`).
[1, 2, 3] === [1, 2, 3] being false is the real problem. I think they'll eventually end up having old and new style objects exactly like what happened in Python2 since there are so many problems with how operators handle objects and how objects work.
I think it's entirely reasonable, they just shouldn't have been added in the first place. Just ignoring the old problems and building more on top of the same sandy base is dangerous and probably negligent.
They don't need to change Map to fix these problems though. It would be able to work with a new form of arrays and/or operator overloading. Reference equality also wouldn't be the end of the world if it was only a default which could be overridden, like Python3 objects.