fun comb(n,m) =
         let
             exception BadN;
             exception BadM;
         in
             if n <= 0 then raise BadN
             else if m < 0 orelse m > n then raise BadM
             else if m=0 orelse m=n then 1
             else comb(n-1,m) + comb(n-1,m-1)
         end;

     SMLofNJ.exportML("newsml");