Earlier quoted context omitted.
I do think we're speaking past each other. I don't fully agree with your "CS sense of the term," as Rust does have a semantically meaningful type: !. This is all pretty bog-standard stuff. Rust isn't doing anything weird or novel here.
I do wonder how many languages have the "never returns" type explicitly available. Typescript and Rust.... Haskell has bottom but I wonder semantically how much space there is between bottom and "never return". Obviously laziness makes things weird. This is what I find interesting in this generation of languages though. Any C programmer understands the notion of an infinite loop, and the value of conditional expressi…
In Scala no one uses "return" (mostly because we don't care about performance in the same way), but if you do, the way it is internally implemented is by throwing exceptions, so in a sense it suffers from the same problems as Rust.
It's actually very important to have that type in a language that uses immutable collections. Imagine this pseudocode:
// List() creates an immutable list
let emptyList = List()
let listWithAnInteger = emptyList.add(42)
let listWithAString = emptyList.add("foo")
This works in Scala. But how can the compiler know that `emptyList.add(42)` is allowed? After all, you can only add things to a list where the added element matches the type of the other elements right?The reason this works is because the type of emptyList will be List and since Nothing a subtype of every other type, the type of listWithAnInteger will become List. You can annotate these types explicitly if you want.
Every language without such a bottom type has a failed type-system in my opinion. (looking at you Golang and many others)