[Haskell-cafe] Policy for taking over a package on Hackage

[wren ng thornton]

On 5/25/11 1:03 PM, Bryan O'Sullivan wrote:
> On Wed, May 25, 2011 at 5:59 AM, Ivan Lazar Miljenovic<
> ivan.miljenovic at gmail.com>  wrote:
>
>> Well, using the Char8 version.
>
> Just because you *could* do that, it doesn't mean that you *should*. It's a
> bad idea to use bytestrings for manipulating text, yet the only plausible
> reason to have wl-pprint handle bytestrings is so that they can be used as
> text.

It's worth highlighting that even with the Char8 version of ByteStrings 
you still run into encoding issues. Remember the days before Unicode 
came about? True, 8-bit encodings are often ASCII-compatible and 
therefore the representation of digits and whitespace are consistent 
regardless of (ASCII-compatible) encoding, but that's still just begging 
for issues. What are the semantics of the byte 0xA0 with respect to 
pretty-printing issues like linewraps? Are they consistent among all 
extant 8-bit encodings? What about bytes in 0x80..0x9F? What about 0x7F 
for that matter?

I won't say that ByteStrings should never be used for text (there are 
plenty of programs whose use of text involves only whitespace splitting 
and moving around the resultant opaque blobs of memory). But at a bare 
minimum, the use of ByteStrings for encoding text needs to be done via 
newtype wrapper(s) which keep track of the encoding. Especially for 
typeclass instances.

-- 
Live well,
~wren