Hi, I've written a program that reads doubles from stdin and creates a distribution of the data according to specified ranges. The program works ok and speed is acceptable (17 secs for 300000 entries), but to run it I have to increase stack size: $ cat input | ./distrib +RTS -K100000000 -RTS How do I figure out why the program needs a lot of stack? Also, is there an easy way to increace performance? Thanks, Patrick import qualified Data.Map as M import Data.List (sort, foldl') import qualified Data.ByteString.Char8 as L import Data.ByteString.Lex.Double data Range n = Range n n | OutOfBounds deriving (Eq, Ord, Show) data Distrib n = Distrib (M.Map (Range n) Int) [Range n] deriving (Show) mkDist :: (Ord n) => [n] -> Distrib n mkDist ns = Distrib M.empty ranges where ranges = zipWith Range l (tail l) l = sort ns record :: (Ord n) => n -> Distrib n -> Distrib n record n (Distrib m rs) = Distrib (M.alter f slot m) rs where f (Just n) = Just $ n + 1 f Nothing = Just 1 slot = findSlot n rs findSlot x (r@(Range a b):rs) | x >= a && x < b = r | otherwise = findSlot x rs findSlot x [] = OutOfBounds mkDouble :: L.ByteString -> Double mkDouble bs = case readDouble bs of Just (d, rest) -> d main = do let d = mkDist [0, 5, 10, 50, 100] bs <- L.getContents let ds = map (abs . mkDouble) . L.lines $ bs let (Distrib m _) = foldr (\n acc -> record n acc) d ds putStrLn . show $ m -- ===================== Patrick LeBoutillier Rosemère, Québec, Canada