On Thu, 6 Sep 2007, Axel Gerstenberger wrote:
module Main where
import System.IO import Text.Printf
main :: IO () main = do let all_results1 = take 20000 $ step [1] --print $ length all_results1 -- BTW: if not commented out, -- all values of all_results -- are already -- calculated here loop [1..50] $ \i -> do let x = all_results1!!i putStrLn $ show i ++ " " ++ show x
The guilty thing is (!!). Better write loop all_results1 $ \x -> do putStrLn $ show i ++ " " ++ show x In your program, the reference to the beginning of the list all_results1 is kept throughout the loop and thus the garbage collector cannot free the memory. ('loop' is available as 'forM_' in GHC-6.6 http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Monad.htm...) See also: http://www.haskell.org/haskellwiki/Things_to_avoid#Lists_are_not_arrays