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# High order functions Challenge 2 of 2 broken

My code is attached and works fine on my Xcode. This basically means there is something wrong in the Treehouse testcase. I deduce this by the fact that there is no compiler warning (meaning it compiles properly?)

higherOrderFunctions.swift
```/**
For this code challenge, let’s define a math operation as a function that
carries out some work on two integers and returns an integer as well. An
example is the function below, `differenceBetweenNumbers`, which takes two
integers and calculates the difference between the numbers. After calculating,
it returns the difference.
*/

func differenceBetweenNumbers(a: Int, b:Int) -> (Int) {
return a - b
}

func mathOperation(operation: (Int, Int) -> Int, a: Int, b: Int) -> (Int){
return operation(a, b)
}

let difference = mathOperation(differenceBetweenNumbers, 5, 2)

```

Nope is not broken. Your code is missing an essential part. And that’s your named parameters. You are calling your function without them.

```// use this instead
let difference = mathOperation(differenceBetweenNumbers, a: 5, b: 2)
```

If you wanted to omit the names so that you didn’t have to use them when calling the function you would have to do something like this.

```func mathOperation(operation: (Int, Int) -> Int, _ a: Int, _ b: Int) -> (Int){
return operation(a, b)
}
```

Hi Jhoan! Unfortunately your solution does not compile at all. The compiler says ("extraneous arguments....").

PS: I also tried that solution myself.

You are right, I apologize. Apparently I am used to working with Swift 2.0 which the first parameter omits it’s external name, and the subsequent parameters don’t by default. In order for you to omit them you have to use the _ .

Try this code, I just did the challenge with it and it worked. I am not exactly sure why yours won’t work other than your return is -> (Int) and mine is -> Int. But I don’t see why that would be a problem.

```func differenceBetweenNumbers(a: Int, b:Int) -> (Int) {
return a - b
}