Task

Take a   Natural Number   in a given base and return the sum of its digits:

   110         sums to   1
   123410   sums to   10
   fe16       sums to   29
   f0e16     sums to   29


fun sumDigits (0, _) = 0
  | sumDigits (n, base) = n mod base + sumDigits (n div base, base)
 
val testInput = [(1, 10), (1234, 10), (0xfe, 16), (0xf0e, 16)]
val () = print (String.concatWith " " (map (Int.toString o sumDigits) testInput) ^ "\n")