(*********************************************************************)
(* Note: this code intentionally contains an error; see text *)
(*********************************************************************)

     fun comb2(n,m) =
             let
                exception OutOfRange of int*int
             in
                if n <= 0 then raise OutOfRange(n,m)
                else if m<0 orelse m>n then
                        raise OutOfRange(n,m)
             else if m=0 orelse m=n then 1
             else comb2(n-1,m) + comb2(n-1,m-1)
     end;

     fun comb(n,m) = comb2(n,m) handle
             OutOfRange(0,0) => 1 |
             OutOfRange(n,m) => (
                     print("out of range: n=");
                     print(Int.toString(n));
                     print(" m=");
                     print(Int.toString(m));
                     print("\n");
                     0
                 );