Mergesort in Swift

gistfile1.swift

let numbers = [9,29, 83, 19, 48, 65, 25, 30, 18, 1, 15, 84, 72, 63, 71]

func splitToSublists(list: [Int]) -> ([Int], [Int]) {
    assert(list.count > 1, "List size must be greater than 1 before split")
    let midIndex = (list.count / 2) as Int
    
    if(list.count == 2) {
        var leftSublist = Array([list[0]])
        var rightSublist = Array([list[1]])
        return (leftSublist, rightSublist)
    }
    else {
    
        var leftSublist: [Int] = Array(list[0...midIndex])
        var rightSublist: [Int] = Array(list[midIndex+1...list.count - 1])
        return (leftSublist, rightSublist)
    }
    
}

func merge(left: [Int], right: [Int]) -> [Int] {
    var result: [Int] = [Int]()
    var list1 = left
    var list2 = right
    
    println(list1)
    
    while(list1.count > 0 || list2.count > 0)
    {
        if(list1.count > 0 && list2.count > 0) {
            if list1[0] <= list2[0] {
              result.append(list1[0])
              list1 = rest(list1)
            }
            else
            {
              result.append(list2[0])
              list2 = rest(list2)
            }
        }
        else if list1.count > 0 {
          result.append(list1[0])
          list1 = rest(list1)
        }
        else {
          result.append(list2[0])
          list2 = rest(list2)
        }
        
    }
    
    return result
}

func rest(list: [Int]) -> [Int] {
    var newList: [Int] = [Int]()

    if(list.count > 1) {
      newList = Array(list[1...list.count-1])
    }
    
    return newList;
    
}

func myMergeSort(list: [Int]) -> [Int] {
    if list.count  > 1 {
        var (leftSublist, rightSublist) = splitToSublists(list)
        
        leftSublist = myMergeSort(leftSublist)
        rightSublist = myMergeSort(rightSublist)
       
        return merge(leftSublist, rightSublist)
    }
    else
    {
        return list
    }
}

var sorted = myMergeSort(numbers)
println("sorted")
println(sorted)
// prints "[1, 9, 15, 18, 19, 25, 29, 30, 48, 63, 65, 71, 72, 83, 84]"