[Haskell-cafe] Ready for testing: Unicode support for Handle I/O
marlowsd at gmail.com
Wed Feb 4 08:31:20 EST 2009
Duncan Coutts wrote:
> On Tue, 2009-02-03 at 11:03 -0600, John Goerzen wrote:
>> Will there also be something to handle the UTF-16 BOM marker? I'm not
>> sure what the best API for that is, since it may or may not be present,
>> but it should be considered -- and could perhaps help autodetect encoding.
> I think someone else mentioned this already, but utf16 (as opposed to
> utf16be/le) will use the BOM if its present.
> I'm not quite sure what happens when you switch encoding, presumably
> it'll accept and consider a BOM at that point.
Yes; the utf16 and utf32 encodings accept a BOM (and generate a BOM in
write mode). This caused interesting bugs when doing re-decoding after
switching encodings, because the BOM constitutes state in the decoder,
which means that decoding is not necessarily repeatable unless you save the
state (which iconv doesn't provide a way to do).
Are there other encodings that have this kind of state? If so, then they
might be restricted to NoBuffering at least when switching encodings.
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