Adding a double to all elements of a numeric array and return Array<Double>-CodePudding

I want to add NumPy like functionality to a Swift array where you can use the or - operators to add/subtract a Double to every element of a numeric Array and return a new Array with the new elements as [Double]. Here is how I have implemented it in 2 extensions for Int and Floating point types:

extension Array where Element: BinaryInteger {
    static func   (array: Self, num: Double) -> [Double]
    {
        return array.map{Double($0)   num}
    }
    
    static func - (array: Self, num: Double) -> [Double]
    {
        return array.map{Double($0) - num}
    }
}

extension Array where Element: BinaryFloatingPoint {
    static func   (array: Self, num: Double) -> [Double]
    {
        return array.map{Double($0)   num}
    }
    
    static func - (array: Self, num: Double) -> [Double]
    {
        return array.map{Double($0) - num}
    }
}

As you can see there is a lot of duplicate code here. Is there a better way to implement this?

I tried this but it doesn't work:

extension Array where Element: Numeric {
    static func   (array: Self, num: Double) -> [Double]
    {
        return array.map{Double($0)   num}
    }
    
    static func - (array: Self, num: Double) -> [Double]
    {
        return array.map{Double($0) - num}
    }
}

The compiler complains at line Double($0) since Double doesn't have initializer for Numeric.

CodePudding user response：

Why use Double at all? You're just introducing potential precision issues for integer types that have perfect precision over integers

extension Array where Element: Numeric {
    static func   (array: Self, num: Element) -> [Element] {
        return array.map { $0   num }
    }
    
    static func - (array: Self, num: Element) -> [Element] {
        return array.map { $0 - num }
    }
}

print([1, 2, 3]   10) // => [11, 12, 13]

CodePudding user response：

I decided to check type of Element and force typecast instead:

extension Array where Element: Numeric {
    static func   (array: Self, num: Decimal) -> [Decimal]
    {
        if let first = array.first {
            switch first {
            case is Int:
                return array.map{Decimal($0 as! Int)   num}
            case is Double:
                return array.map{Decimal($0 as! Double)   num}
            case is Decimal:
                return array.map{$0 as! Decimal   num}
            default:
                break
            }
        }
        
        return []
        
    }
    
    static func - (array: Self, num: Decimal) -> [Decimal]
    {
        if let first = array.first {
            switch first {
            case is Int:
                return array.map{Decimal($0 as! Int) - num}
            case is Double:
                return array.map{Decimal($0 as! Double) - num}
            case is Decimal:
                return array.map{$0 as! Decimal - num}
            default:
                break
            }
        }
        
        return []
        
    }
    
    static func / (array: Self, num: Decimal) -> [Decimal]
    {
        if let first = array.first {
            switch first {
            case is Int:
                return array.map{Decimal($0 as! Int) / num}
            case is Double:
                return array.map{Decimal($0 as! Double) / num}
            case is Decimal:
                return array.map{$0 as! Decimal / num}
            default:
                break
            }
        }
        
        return []
        
    }
}