[Haskell-cafe] Re: Writing binary files?

[Glynn Clements]

Udo Stenzel wrote:

> > > One more reason to fix the I/O functions to handle encodings and have
> > > a seperate/underlying binary I/O API.
> > 
> > The problem is that we also need to fix them to handle *no encoding*.
> 
> What are you proposing here?  Making the breakage even worse by specifying
> a text based api that uses "no encoding"?  

No. I'm suggesting that many of the I/O functions shouldn't be
treating their arguments or return values as text.

> Having a seperate byte based api is far better. If you don't know
> the encoding, all you have is bytes, no text.

My point is that many of the existing functions should be changed to
use bytes instead of text (not separate byte/char versions). E.g.:

	type FilePath = [Byte]

If you have a reason to treat a FilePath as text, then you convert it.
E.g.

	names <- getDirectoryContents dir
	let namesT = map (toString localeEncoding) names

We don't need a separate getDirectoryContentsAsText, and we certainly
don't want that to be the default.

For stream I/O, then having both text and binary read/write functions
makes sense.

> > >  String's are a list of unicode characters, [Word8] is a
> > > list of bytes.
> > 
> > And what comes out of (and goes into) most core library functions is
> > the latter.
> 
> So System.Directory needs to be specified in terms of bytes, too.  Looks like
> a clean solution to me.

Sure. But I'm looking for a solution which doesn't involve re-writing
everything, and which won't result in lots of programs suddenly
becoming unreliable if the hardwired default ISO-8859-1 conversion is
changed.

-- 
Glynn Clements <glynn.clements at virgin.net>