> Is it possible to implement foo? Trivially, the answer is no, as Void is a type that contains no values, so it’s impossible for any function to produce a value of type Void

That's actually not really correct. Or rather, it is technically correct but it will confuse the readers who work in languages like Java.

While void in languages like Java means that the result of the function cannot be used or has no meaning, it is NOT equivalent to types like the bottom type of Haskell. Because that would mean that the function can never return.

Rather, void is similar to the "unit type" (https://en.wikipedia.org/wiki/Unit_type) which does have a value. It's like an empty tuple. It contains no information other then "the function call has finished". (and of course in languages with exceptions, this means that no exception was thrown)

Otherwise, I like the article. More people should read and understand this way of thinking.