Can't say that I see the value in that but you do have the option of adding types the old fashion way.

    let s = "Swift is the future"
    let s:String = "Swift is the future"

It's just a matter of making a coding convention.

You can just alt-click on the variable in Xcode and see the inferred variable type instantly, no matter what the type is or where the variable is declared. No need to search. You can't do this in Objective-C.

Well you can see that s is a string because of the assignment, and if you want you can also add type annotations like

let s: String = "Swift is the future"