A sample quiz answer on how to create toString without relying on primitive toString method for integers

toString.scala

def customToString(x: Int): String = {
  val digits: Array[Char] = Array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9')
  def recur(base: Int, digit: Int, accu: List[Char]): List[Char] = {
    val newAcc = digits(digit) :: accu
    if (base == 0) newAcc
    else recur(base / 10, base % 10, newAcc)
    }
  val absX = math.abs(x)
  val toCharList = recur(absX / 10, absX % 10, List.empty)
  if (x < 0) ('-' :: toCharList).mkString
  else toCharList.mkString
}

here's my solution in Haskell

toString :: Int -> String
toString n
  | i < 10 = [ ['0'..'9'] !! i ]
  | otherwise = sign ++ toString(i `div` 10) ++ toString(i `mod` 10)
  where i = abs n
        sign = if n < 0 then ['-'] else []