prefix operator prefix + { associativity precedence } Declarations prefix func +(_: Double) Declaration prefix func +(x: Double) -> Double prefix func +(_: Float) Declaration prefix func +(x: Float) -> Float prefix func +(_: Float80) Declaration prefix func +(x: Float80) -> Float80 prefix func + <T : SignedNumberType>(_: T) Declaration prefix func +<T : SignedNumberType>(x: T) -> T