gistfile1.hs

halp :: Int -> IO [Int]
halp 0 = return []
halp a = do
    putStrLn "Tick in IO [Int]"
    y <- halp (a - 1)
    return $ 1 : y

halphalp :: Int -> [IO Int]
halphalp n = replicate n $ (putStrLn "Tick in [IO Int]" >> return 1)

main = do
  putStrLn "The behavior of IO [Int]"
  x <- halp 5
  putStrLn (show $ head x)
  -- We saw 5 ticks but printed only the first value.
  putStrLn "The behavior of [IO Int]"
  let y = halphalp 5 -- Note that this is a let, not a do! 
  z <- head y        -- Now let's execute ONE of these.
  putStrLn (show z)  -- We only saw one tick.