Re: [Haskell-cafe] Core packages and locale support

* Brandon S Allbery KF8NH [2010-06-25 05:00:08-0400]

On 6/25/10 02:42 , Roman Cheplyaka wrote:

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* Jason Dagit [2010-06-24 20:52:03-0700]

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On Sat, Jun 19, 2010 at 1:06 AM, Roman Cheplyaka wrote:

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While ghc 6.12 finally has proper locale support, core packages (such as unix) still use withCString and therefore work incorrectly when argument (e.g. file path) is not ASCII.

Pardon me if I'm misunderstanding withCString, but my understanding of unix paths is that they are to be treated as strings of bytes. That is, unlike windows, they do not have an encoding predefined. Furthermore, you could have two filepaths in the same directory with different encodings due to this.

you got everything right here. So, as you said, there is a mismatch between representation in Haskell (list of code points) and representation in the operating system (list of bytes), so we need to know the encoding. Encoding is supplied by the user via locale (https://secure.wikimedia.org/wikipedia/en/wiki/Locale), particularly LC_CTYPE variable.

You might want to look at how Python is dealing with this (including the pain involved; best to learn from example).

Do you mean the pain when filenames can not be decoded using current locale settings and thus the files are not accessible? (The same about environment variables.) Agreed, it's unpleasant. The other way would be changing [Char] to [Word8] or ByteString. But this would a) break all existing programs and b) be an OS-specific hack. Crap. Brandon, do you have any ideas on how we should proceed with this? -- Roman I. Cheplyaka :: http://ro-che.info/ "Don't let school get in the way of your education." - Mark Twain