alt Hacker News> There are several literals in that code snippet; I could annotate them with their types, and this code would still be exactly as it is.
Well, no, there is one literal that has an ambiguous type, and if you annotated its type, it would resolve entirely the question of what a typechecker should say; literally the entire reason it is an open question is because that one literal is not annotated.
True, you could annotate 3 of the 4 literals in this without annotating the List, which is ambiguous. In the absence of an explicit annotation (because those are optional), type checkers are left to guess intent to determine whether you wanted a List[Any] or List[number | string], or whether you wanted a List[number] or List[string].