[Haskell-cafe] Writing binary files?

Glynn Clements glynn.clements at virgin.net
Sun Sep 12 09:24:56 EDT 2004

Sven Panne wrote:

> > [...]
> > 	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 <glynn.clements at virgin.net>

More information about the Haskell-Cafe mailing list