> "functional" (which means it has immutable values I guess?)

No, it means that it's a functional language. Please consult google if you are not sure what that means.

> "pretty good type system" (which means it has generics?)

No, it means that it has a more advanced type system than any of the languages you mentioned. It's most likely the most popular language with a type system that can be considered somewhat advanced.

There might be idiosyncrasies but like compared with say JS or whatever it's still miles ahead.

Yeah, the standard library is somewhat lacking but like that will be fixed. The language is very solid though.

Also don't judge a language by lack of an HTTP server in the standard library.