Re: problems with working with Handles

[Niels Reyngoud]

Hello all,

Thanks for your replies on our previous posts. To avoid the lazy 
behaviour, we tried to write our own IO module "IOExts2" which basically 
redifnes
readFile, writeFile and appendFile to make sure they use binary-mode and 
strict behaviour. The libary is as follows:

----------
module IOExts2(readFile', writeFile', appendFile') where
import IO
import IOExts
readFile' :: String -> IO String
readFile' inputfile = do readhandle <- openFileEx inputfile (BinaryMode 
ReadMode)
            x <- hGetContents readhandle
            seq x (return x)
      {-      seq x (do hClose readhandle
                      return x) -}
            

writeFile' :: String -> String -> IO()
writeFile' outputfile text = seq text (writeFile'' outputfile text)
writeFile'' :: String -> String -> IO()
writeFile'' outputfile text = do writehandle <- openFileEx outputfile 
(BinaryMode WriteMode)
                                hPutStr writehandle text
                     hFlush writehandle
                       hClose writehandle

appendFile' :: String -> String -> IO()
appendFile' outputfile text = seq text (appendFile'' outputfile text)
appendFile'' :: String -> String -> IO()
appendFile'' outputfile text = do appendhandle <- openFileEx outputfile 
(BinaryMode AppendMode)
                                 hPutStr appendhandle text
                     hFlush appendhandle
                     hClose appendhandle

---------------

Yet, there's still one problem left with readFile'. The handles of 
appendFile' and writeFile' are properly closed, but when I try to close 
the handle used for reading (as shown by the parts
commented above) and try the following small test, which uses a file 
"123.txt"  that consists of the string "blaat" only a "b" is outputted. 
When  I do not close the handle, the entire string "blaat" is outputted.

test = do x <- readFile' "123.txt"
             putStr x
Regards,
Niels Reyngoud
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