Haskell Program: hailstone :: Integer -> Integer

Given a positive integer n, return the length of the hailstone sequence beginning with n. The hailstone sequence for an integer n can be found by repeatedly applying a specific function. We will write e[i] for element i in the sequence, and define: e[0] = n e[i+1] = e[i] / 2, if e[i] is even e[i+1] = 3 * e[i] + 1, if e[i] is odd The sequence ends once e[i] is 1. Thus, the hailstone sequence for 3 is [3,10,5,16,8,4,2,1], and the length of the sequence is 8.