I'm playing around with Haskell and writing files. Here is a little piece of code that for every "blue" in [0..255] creates an image in PPM with "red" and "green" in [0..255]. It produces within a folder all images.
This little program makes my computer crash buy using more than 5 gB of memory and I don't know why. What I asked him to do seems pretty simple for me and the total space taken by generated images is - 200 mB ... and don't understand why memory explodes.
Here is the code :
import System.Directory
import Data.Colour.SRGB
import Data.List.Split
gridColours = [[RGB 255 0 0, RGB 0 255 0], [RGB 0 0 255, RGB 0 0 0]]
gridColours2 b = chunksOf 256 [RGB r g b| r <- [0..255], g <- [0..255]]
dimensions l = (length . head $ l, length l)
coupleToList (a,b) = [a,b]
genDataLines list = unwords . (map showColour) . concat $ list
genDims list = unwords . (map show) . coupleToList . dimensions $ list
writePPM list path = writeFile path $ unwords $ ["P3", genDims list, "255", genDataLines list]
showColour c = unwords . (map show) $ [channelRed c, channelGreen c, channelBlue c]
main = do
createDirectoryIfMissing True "/tmp/PPM-out/"
mapM_ (\x -> writePPM (gridColours2 x) ("/tmp/PPM-out/image"++(show x)++".ppm")) [0..255]
A perfect answer would explain me what I did wrong and give me advices about how to solve this problem of memory to my system from crashing.
Thank you.
