Re: behaviour change in getDirectoryContents in GHC 7.2?

On Wed, Nov 02, 2011 at 01:29:16PM +0000, Max Bolingbroke wrote:

On 2 November 2011 10:03, Jean-Marie Gaillourdet wrote:

...

As far as I know, not all encodings are reversable. I.e. there are byte sequences which are invalid utf-8. Therefore, decoding and re-encoding might not return the exact same byte sequence.

The PEP 383 mechanism explicitly recognises this fact and defines a reversible way of decoding bytes into strings. The new behaviour is guaranteed to be reversible except for certain private use codepoints (0xEF00 to 0xEFFF inclusive) which: 1. We do not expect to see in practice 2. Are unofficially standardised for use with this sort of "encoding hack"

I don't understand this. If I understand correctly, you use U+EF00-U+EFFF to encode the characters 0-255 when they are not a valid part of the UTF8 stream. So why not encode U+EF00 (which in UTF8 is 0xEE 0xBC 0x80) as U+EFEE U+EFBC U+EF80, and so on? Doesn't it then become completely reversible? Thanks Ian