So variables are explicitly declared, don't have issues of mis typing a variable name and accidentally declaring a new one.

Note: This is just my thinking, I don't know if it's the actual reason

That's a sensible reason, sure, but I'd rather declare it with an actual type instead.

Yes, for complicated things like this, explicitly declaring the type is probably preferable.

As opposed to doing what?

Like python, just `e = equal(...`

Python had to go through a lot of pain for that, the "nonlocal" keyword was only added in Python 3.0, and the local/global distinction is very fragile.

Javascript and Coffeescript try to solve this in different ways, most people think that JavaScript's method sucks, and many are not fond of CoffeeScript's non-locality. Personally, I think that demanding variable declaration is still the best option (possibly except for interactive sessions).