L.S., After reading through 60 or 61 files (about 220 kB), Hugs fails with the message: (1426170 reductions, 2976893 cells, 68 garbage collections) ERROR - Garbage collection fails to reclaim sufficient space This is done with the program below (ReadALot.lhs), which reads a series of files (these files are listed in dir.dat). The program reads the first and the last (non-empty) line of each file and writes them, together with the filename in the output file result.dat. The program works fine when compiled with GHC, it then reads 2946 files without a problem. More info.: System: Windows 98 Hugs version: Nov 2002 Best regards, Henk-Jan van Tuyl ====================================================================== ReadALot.lhs Read a lot of files 2003-10-06 History: 031009 Added dummy parameter to "main" ====================================================================== import IO import Monad inputSet :: String inputSet = "dir.dat" outputFile :: String outputFile = "result.dat" ====================================================================== main ====================================================================== main :: a -> IO () main _ = do hInputSet <- openFile inputSet ReadMode hOutputFile <- openFile outputFile WriteMode fileNames <- hGetContents hInputSet allData <- collectAllData $ lines fileNames hPutStrLn hOutputFile $ unlines allData hClose hInputSet hClose hOutputFile ====================================================================== collectAllData Read a list of file names and return file name, first line and last line of each file in a list ====================================================================== collectAllData :: [String] -> -- A list of filenames IO [String] -- A list of results collectAllData [] = return [] collectAllData (fileName : fileNames) = do putStrLn $ "Reading: " ++ fileName h <- openFile fileName ReadMode contents <- hGetContents h dataFromFile <- return $! parseFile $ filter (/= "") $ lines contents let (firstLine, lastLine) = dataFromFile To force reading of the file before closing, we add a "when" (from the Monad library), with a boolean expression that uses lastLine and will always be true: when (length lastLine >= 0) $ hClose h rest <- collectAllData fileNames return $ fileName : firstLine : lastLine : "" : rest ====================================================================== parseFile Returns the first and the last string of a list of strings, as a tuple ====================================================================== parseFile :: [String] -> (String, String) parseFile [] = ("", "") parseFile [x] = (x, "") parseFile (x : xs) = (x, last xs) --