It is not much in other languages because those languages are old. A lot of the Swift features have been in more academic functional languages for a long time.

It is not much in other languages because those languages are old. A lot of the Swift features have been in more academic functional languages for a long time. However it has taken time for the mainstream languages to adopt these ideas. The industry moves much slower than academic niche languages. But most new languages has some variant of this stuff: kotlin, scala, rust. I program a lot in Julia which is a script language and it does not have allow you to use null freely either. May seem odd for a language that does not type check at compile time. But it actually makes sense.