Haskell lazy async

lazy-async.hs

import Control.Concurrent.Async                                                 
import Control.Monad                                                            
                                                                                
sites = ["http://www.google.com",                                               
         "http://www.bing.com",                                                 
         "http://www.yahoo.com",                                                
         "http://www.wikipedia.com/wiki/Spade",                                 
         "http://www.wikipedia.com/wiki/Shovel"]                                
                                                                                
printRepeat :: String -> IO [String]                                            
printRepeat url = do                                                            
  return $ repeat url                                                           
                                                                                
main = do                                                                       
  as <- mapM (async . printRepeat) sites                                        
  xs <- mapM wait as                                                            
  forM_ xs $ putStrLn . ("Got: " ++) . head