Sieve

I have been learning Haskell for a mere two weeks in class, but am already quite delighted with it. Here is one of the toy programs I wrote today.

{-
sieve.hs, Haskell implementation of sieve of Eratosthenes:
http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes

this program is somewhat sub-optimal--e.g., I find all the composite numbers to n * p, rather than n.
I blame the fact that 
1. this is totally for fun
2. I'm still very n00b at Haskell 
-}

doSieve n = [p | p <- [2, 3 .. n] , not (p `elem` (compositeNumb n 2))]

compositeNumb n p =
 if n < p^2
  then []
  else ([p * mults | mults <- [2, 3.. n]]) ++ compositeNumb n (p + 1)