Re: [Haskell-cafe] Writing binary files?

Abraham Egnor wrote:

Passing a Ptr isn't that onerous; it's easy enough to make functions that have the signature you'd like:

import System.IO import Data.Word (Word8) import Foreign.Marshal.Array

hPutBytes :: Handle -> [Word8] -> IO () hPutBytes h ws = withArray ws $ \p -> hPutBuf h p $ length ws

hGetBytes :: Handle -> Int -> IO [Word8] hGetBytes h c = allocaArray c $ \p -> do c' <- hGetBuf h p c peekArray c' p

If it's that simple, why don't the libraries provide it? It would save a lot of traffic on haskell and haskell-cafe alone. :-) -Jan-Willem Maessen

On Sun, 12 Sep 2004 14:24:56 +0100, Glynn Clements wrote:

...

Sven Panne wrote:

...

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[...] main :: IO () main = do h <- openBinaryFile "out.dat" WriteMode hPutStr h $ map (octetToChar . bitsToOctet) bits hClose h

Hmmm, using string I/O when one really wants to do binary I/O gives me a bad feeling. Haskell characters are defined to be Unicode characters, so the above only works because current Haskell implementations usually get this wrong (either no Unicode support at all and/or ignoring any encodings and doing I/O only with the lower 8 bits of the characters)... hGetBuf/hPutBuf plus their non-blocking variants are the only way to *really* do binary I/O currently.

Which is unfortunate, because of the requirement to pass a Ptr. We really need "hPutBytes :: [Word8] -> IO ()" etc.

Also, changing the existing functions to deal with encodings is likely to break a lot of things (i.e. anything which reads or writes data which is in neither UTF-8 nor the locale-specified encoding).

-- Glynn Clements _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

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