switch is not an expression? what?

pm.swift

enum Either<T, V> {
    case Left(T)
    case Right(V)
}

var lint: Either<Int, Any> = Either.Left(42)
var rstring: Either<Any, String> = Either.Right("at you")

switch rstring {
    case .Right(let x): print("right", x)
    case .Left: print("not right")
}

/*
 * <stdin>:15:37: error: expected expression in list of expressions
 *  print("is this not an expression?", switch lint {
 *  ^
 * <stdin>:15:37: error: expected ',' separator
 * print("is this not an expression?", switch lint {
 * ^
 */
print("is this not an expression?", switch lint {
    case .Left: "left"
    case .Right: "right"
})