#70: some vs any in Swift

A quick mental model: some means “one concrete type, hidden from you”, while any means “a box that can hold values of any conforming type”.

func makeID() -> some Hashable { 42 }
let value: any Hashable = 42

With some, the implementation chooses a concrete type and sticks to it. With any, the concrete type can vary at runtime.

That simple distinction explains most of the behavior you will see in practice.