Load File: __prime.sml

   This module defines a function, testPrime, which tests whether a 
   given integer is a prime number.  It illustrates the use of the 
   LargeInt structure in the basis library.

   The module uses Fermat's algorithm to test for primes.  The second
   argument to testPrime controls the number of integers to which the
   algorithm is applied.  Although a given number of successful tests 
   do not guarantee that the first argument is prime, if the number of 
   tests is not too small, then the result is very likely to be correct.

   For example, to apply the algorithm to the first 15 integers to see 
   whether 233 is a prime:

      Prime.testPrime (233, 15);

   gives

      val it : bool = true