Task

Write a boolean function that tells whether a given integer is prime using Wilson's theorem.

By Wilson's theorem, a number p is prime if and only if p divides (p - 1)! + 1.

Remember that 1 and all non-positive integers are not prime.



See also

 Cut-the-knot: Wilson's theorem.
 Wikipedia: Wilson's theorem


 
   wilson=: 0 = (| !&.:<:)
   (#~ wilson) x: 2 + i. 30
2 3 5 7 11 13 17 19 23 29 31
 