// Some simple programs in ATS
// Hongwei Xi (Oct 12, 2005)

staload "ATS/stdio.sats"

// typedef Nat = [n:int | n > 0] int (n)

fun fact {n:nat} .<n>. (n: int n): Nat =
  if n igt 0 then n nmul fact (n isub 1) else 1

val _ = begin
  print_string "The value of fact(10) = ";
  print_int (fact 10);
  print_newline ()
end

fun ack {m:nat, n:nat} .<m,n>.
   (m: int m, n: int n): Nat =
  if m igt 0 then
    if n igt 0 then ack (ipred m, ack (m, ipred n))
    else ack (ipred m, 1)
  else isucc n

val _ = begin
  print_string "The value of ack(3, 5) = ";
  print_int (ack (3, 5));
  print_newline ()
end