Numeric

The Numeric protocol provides a suitable basis for arithmetic on scalar values, such as integers and floating-point numbers. You can write generic methods that operate on any numeric type in the standard library by using the Numeric protocol as a generic constraint.

The following example extends Sequence with a method that returns an array with the sequence’s values multiplied by two.

extension Sequence where Element: Numeric {
    func doublingAll() -> [Element] {
        return map { $0 * 2 }
    }
}

With this extension, any sequence with elements that conform to Numeric has the doublingAll() method. For example, you can double the elements of an array of doubles or a range of integers:

let observations = [1.5, 2.0, 3.25, 4.875, 5.5]
let doubledObservations = observations.doublingAll()
// doubledObservations == [3.0, 4.0, 6.5, 9.75, 11.0]

let integers = 0..<8
let doubledIntegers = integers.doublingAll()
// doubledIntegers == [0, 2, 4, 6, 8, 10, 12, 14]

To add Numeric protocol conformance to your own custom type, implement the required initializer and operators, and provide a magnitude property using a type that can represent the magnitude of any value of your custom type.