Adding any two numberic tuples in swift

user_5215474 0
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I have created one function to add tuples which looks like (Int, Int).

func +<T : Numeric> (x: (T, T), y: (T, T)) -> (T, T) {
    return (x.0 + y.0, x.1 + y.1)
}

It works for (10, 20) + (15, 15)

Now what I need is to make an advancement to function to accept any variable length tuples of same length.

How is possible way?

At the end (12) + (23) and (10, 12, 16) + (11, 36, 25) should work.

swift generics ios
2 Answers

Tuples need to have their number of elements determined at compile time, thus a variadic-like function won't work. You'll need to add overrides for the + operator, for each tuple size you need to support:

func +<T : Numeric> (x: (T, T), y: (T, T)) -> (T, T) {
    return (x.0 + y.0, x.1 + y.1)
}

func +<T : Numeric> (x: (T, T, T), y: (T, T, T)) -> (T, T, T) {
    return (x.0 + y.0, x.1 + y.1, x.2 + y.2)
}

func +<T : Numeric> (x: (T, T, T, T), y: (T, T, T, T)) -> (T, T, T, T) {
    return (x.0 + y.0, x.1 + y.1, x.2 + y.2, x.3 + y.3)
}

// and so on, ...

Alternatively, you can switch to other data types, like arrays, which allow a dynamic number of items:

infix operator ++ 

func ++<T: Numeric>(_ lhs: [T], _ rhs: [T]) -> [T] {
    return zip(lhs, rhs).map { $0.0 + $0.1 }
}

print([10, 12, 16] ++ [11, 36, 25]) // [21, 48, 41]

Caveats of this approach:

  • you need to use a different operator, since is + already defined for arrays, and it concatenates the arrays instead of individually summing the corresponding elements
  • if the two arrays have different sizes, then the result will have the size of the smaller arrays of the two input ones.
user_19742240

You can use the Array solution as suggested by @Cristik or you can also make use of closure returning variadic function like:

func add<T : Numeric>(_ a: T...) -> (_ b: T...) -> [T] {
    return { (b: T...) -> [T] in
        return zip(a, b).map { $0.0 + $0.1 }
    }
}

let sum = add(1, 2,3)(4, 5, 6)

print(sum)
user_75681160
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