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 : FloatingPoint>(_: T) Declaration prefix func -<T : FloatingPoint>(x: T) -> T prefix func - <T : SignedNumber>(_: T) Declaration prefix func -<T : SignedNumber>(x: T) -> T