Minor update, here's how I would handle this problem (using uu-parsinglib and the latest ListLike, mostly untested): import Data.ListLike (fromString, CharString (..)) import Text.ParserCombinators.UU import Text.ParserCombinators.UU.BasicInstances import Text.ParserCombinators.UU.Utils -- change the local bindings in undumpFile to: addv m s | BS.null s = m addv m s = let (k,v) = readKV s in Map.insert k v m readKV :: BS.ByteString -> (BS.ByteString, BS.ByteString) readKV s = let [ks,vs] = parse (pTuple [pQuotedString, pQuotedString]) (createStr (LineColPos 0 0 0) $ CS s) unCSf = BS.drop 1 . BS.init . unCS in (unCSf ks, unCSf vs) And of course change the type of "foldLines" and use BS.hGetLine, both to enable ByteString IO. To use uu-parsinglib's character parsers (e.g. pTuple) with ByteStrings, you need to use a newtype wrapper such as CharString from ListLike, "CS" and "unCS" wrap and unwrap the type. The "unCSf" function removes the starting and trailing quotes in addition to unwrapping. This is still quick-and-dirty in that there's no error recovery, but it's easy to add, just see the uu-parsinglib documentation and examples, particularly "pEnd". I think this will make a significant difference to your application. John L. Message: 4

Date: Tue, 22 Mar 2011 20:32:16 -0600 From: Tim Docker Subject: memory slop (was: Using the GHC heap profiler) To: glasgow-haskell-users@haskell.org Message-ID: <4D895BB0.1080902@dockerz.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed

-------- Map2.hs --------------------------------------------

module Main where

import qualified Data.Map as Map import qualified Data.ByteString.Char8 as BS import System.Environment import System.IO

type MyMap = Map.Map BS.ByteString BS.ByteString

foldLines :: (a -> String -> a) -> a -> Handle -> IO a foldLines f a h = do eof <- hIsEOF h if eof then (return a) else do l <- hGetLine h let a' = f a l a' `seq` foldLines f a' h

undumpFile :: FilePath -> IO MyMap undumpFile path = do h <- openFile path ReadMode m <- foldLines addv Map.empty h hClose h return m where addv m "" = m addv m s = let (k,v) = readKV s in k `seq` v `seq` Map.insert k v m

readKV s = let (ks,vs) = read s in (BS.pack ks, BS.pack vs)

dump :: [(BS.ByteString,BS.ByteString)] -> IO () dump vs = mapM_ putV vs where putV (k,v) = putStrLn (show (BS.unpack k, BS.unpack v))

main :: IO () main = do args <- getArgs case args of [path] -> do v <- undumpFile path dump (Map.toList v) return ()