[vimslayer]

Elm doesn't need to perform runtime checks (apart from application boundaries like JSON parsing, where runtime checks are performed) because their type system is supposed to be sound, so you can't compile something that would have incorrect types at runtime. Or if you can, that's considered a bug in the compiler. That kind of sound type system has never been a goal for TypeScript.

Note that I'm not saying that Elm would be better than TS or any other language or anything like that, just commenting about the runtime checks. Obviously languages have their strengths and weaknesses (Elm has plenty of both) and TS has had good reasons to go with their design goals.