Haskell port of OCaml http://pastebin.com/a66MDZkP

tga.hs

{-|
    Haskell port of OCaml http://pastebin.com/a66MDZkP
-}
import qualified Data.ByteString.Lazy as B
import Data.Word8

type Point = (Double, Double)
type Rgb = (Double, Double, Double)

tga :: (Point -> Rgb) -> Int -> Int -> String -> IO ()
tga f width height path = do
    B.writeFile path (B.pack contents')
    where
        pxs = [((adjust x width),(adjust y height)) | y <- [0..height-1], x <- [0..width-1]]
        pxs' = fmap f pxs
        adjust p dim = ((toDouble p) - (toDouble dim) / 2) / (toDouble dim)
        header =
            [0,0,2,0,0,0,0,0,0,0,0,0,
                width `mod` 256, truncate (toDouble width / 256),
                height `mod` 256, truncate (toDouble height / 256),
                24,0]
        contents = header ++ (concat $ fmap (\(r,g,b) -> asByte b : asByte g : [asByte r]) pxs')
        contents' = fmap toWord8 contents
        asByte x = min 255 (max 0 (truncate (128.0 * (x + 1.0))))
        toWord8 x = (fromIntegral x) :: Word8
        toDouble x = (fromIntegral x) :: Double
        
main :: IO ()
main = do
    tga (\(x,y) -> (sin x, sin y, x * y)) 640 480 "/Users/giacomo/temp/x.tga"
    putStrLn "done."