Scala Type Syntax

Question

I\'ve observed that, if I want to make a generic function that can accept a list of any type and return a boolean, I can use the following syntax for a function declaration:

Answer 1

List[_] is an unconstrained existential type and shorthand for List[X] forSome {type X <: Any} (which is like List in Java).

In this case, I think the function types (not in Scala syntax) forall A. List[A] -> Boolean and (exists A. List[A]) -> Boolean denote the same things, since in both cases you can only inspect the "shape" of the list; probably there's an equivalence between those types.