Simple example showing Function Currying in swift

swiftFunctionCurry.swift

// (Int, Int) -> Int
func add(num1: Int, num2: Int) -> Int {
    return num1 + num2
}

// increment just adds to any other number
let curried: (Int) -> ((Int) -> Int) = { num in
    return { num2 in
        return add(num1: num, num2: num2)
    }
}

func curry(inputFunc: @escaping ((Int, Int) -> Int)) -> ((Int) -> ((Int) -> Int)) {
    return { a in
        return { b in
            inputFunc(a, b)
        }
    }
}

let curriedAdd = curry(inputFunc: add)
let inc = curriedAdd(1)
inc(5) // 6