sumitokamoi

extension Array {
    func chunked(by chunkSize: Int) -> [[Element]] {
        return stride(from: 0, to: self.count, by: chunkSize).map {
            Array(self[$0..<Swift.min($0 + chunkSize, self.count)])
        }
    }
}

let arr = [0,1,2,3,4,5,6,7,8,9]
print(arr.chunked(by: 2)) // [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9]]

sumitokamoi

var nums = (10...19)
let result = nums.enumerated().flatMap { [count = nums.count, x = 10] (offset: Int, element: Int) -> [Int] in
    if offset < count / 2 {
        return []
    }
    return [element, element-x]
}
print(result) // [15, 5, 16, 6, 17, 7, 18, 8, 19, 9]

sumitokamoi

quicksort :: (Ord a) => [a] -> [a]
quicksort [] = []
quicksort (x:xs) =
  let smallOrEqual = filter (<= x) xs
      larger = filter (> x) xs
   in quicksort smallOrEqual ++ [x] ++ quicksort larger