-- This program implements Eratosthenes Sieve
 -- to generate prime numbers.
 
 module Main where
 
 primes :: [Int]
 primes = map head (iterate sieve [2 ..])
 
 sieve :: [Int] -> [Int]
 sieve (p:ps) = [x | x <- ps, (x `mod` p) /= 0]
 
 main = appendChan stdout "How many primes? " abort $
        readChan stdin abort $ \ input ->
        appendChan stdout (show (take (read (head (lines input))) primes))
 	                 abort done