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USER DEFINED EXCEPTIONS



exception BadN;

	exception BadN

exception BadM;

	exception BadM

fun comb ( n, m ) =
	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 );

	val comb = fn : int * int -> int


comb ( 5, 2 );

	val it = 10 : int
	
comb ( ~1, 0 );

	uncaught exception BadN
	
comb ( 5, 6 );

	uncaught exception BadM