But this particular chain started as a discussion of how sum types are missed in every other language. Isn't that a very important observation? Every programmi

But this particular chain started as a discussion of how sum types are missed in every other language. Isn't that a very important observation? Every programming language is an experiment: it tests whether an well-defined, particular model of computation ends up having advantages on human engineering results. Maybe it causes fewer bugs. Maybe it makes development faster. Maybe it makes certain features easier to implement. So whether one language has a feature that's highly missed in other languages is the very basis of the debate. I personally am not a Rust programmer, but not knowing Rust, but knowing another programing language that has sum types, it seems understable to me that it worths mentioning this for every language that doesn't have sum types. And when you do do that you might as well mention Rust as an example. (Maybe because it's more mainstream?)