Programming performance/ArthurVanLeeuwen Haskell

{{{ main = do xs <- getContents

         let cashheld = runStrategy 10000 . reverse . getDays . filter (\l -> head l /= '#') . filter (not . null) $ lines xs
         putStrLn $ "Cash held: " ++ show cashheld

getDays :: [String] -> [(String,Double,Double,Double,Double,Integer,Double)] getDays = map getDay

getDay :: String -> (String,Double,Double,Double,Double,Integer,Double) getDay s = getDay' $ words s

   where getDay' [date,open,high,low,close,volume,adjustedclose] = (date,read open,read high,read low,read close,read volume,read adjustedclose)

runStrategy cash lines = runStrategy' cash lines []

runStrategy' cash lines shares =

   case lines of
       (c1:c2:_) -> if (closing c2 - closing c1) / closing c1 < - 0.03 then
                       runStrategy' (cash * 0.9) (tail lines) ((((cash * 0.1) / closing c2), closing c2): shares)
                    else if not . null $ shares then
                            if (closing c2 - (snd . head $ shares)) / (snd . head $ shares) > 0.06 then
                               runStrategy' (cash + (fst . head $ shares) * closing c2) (tail lines) (tail shares)
                            else runStrategy' cash (tail lines) shares
                         else runStrategy' cash (tail lines) shares
       [c1] -> cash + sellOff (closing c1) shares
       [] -> cash

sellOff price shares = sum . map (* price) . map fst $ shares

closing (date,open,high,low,close,volume,adjustedclose) = close }}}