\begin{verbatim}
(* Program for generating primes upto some number *)

local
    fun primeWRT (m, []) = true
      | primeWRT (m, h::t) = if m mod h = 0 then false
			     else primeWRT (m, t)

    fun generateFrom (P, m, n) = 
	if m > n then P
	else if primeWRT (m, P)
	then ( print (Int.toString (m)^" is a prime\n");
	       generateFrom ((m::P), m+2, n)
	     )
	else generateFrom (P, m+2, n)

in fun primesUpto n = 
       if n < 2 then []
       else if n=2 then [2]
       else if (n mod 2 = 0) then primesUpto (n-1)
       else generateFrom ([2], 3, n);
end
\end{verbatim}