[Haskell-cafe] Re: Strings and utf-8

Jules Bean jules at jellybean.co.uk
Thu Nov 29 08:05:19 EST 2007

Duncan Coutts wrote:
> On Wed, 2007-11-28 at 17:38 -0200, Maurí­cio wrote:
>>>> (...)  When it's phrased as "truncates to 8
>>  >> bits" it sounds so simple, surely all we need
>>  >> to do is not truncate to 8 bits right?
>>  >>
>>  >> The problem is, what encoding should it pick?
>>  >> UTF8, 16, 32, EBDIC? (...)
>>  >>
>>  >> One sensible suggestion many people have made
>>  >> is that H98 file IO should use the locale
>>  >> encoding and do Unicode/String <-> locale
>>  >> conversion. (...)
>> I'm really afraid of solutions where the behavior
>> of your program changes with an environment
>> variable that not everybody has configured
>> properly, or even know to exist.
> Be afraid of all your standard Unix utils in that case. They are all
> locale dependent, not just for encoding but also for sorting order and
> the language of messages.

Language of messages is quite different from language of a file you read.

Suppose I am English, and I have a russian friend, Vlad.

My default locale is, say, latin-1, and his is something cyrillic.

I might well open files including my own files, and his files. The 
locale of the current user is simple no guide to the correct encoding to 
read a file in, and not a particularly reliable guide to writing a file out.

Locale makes perfect sense for messages (you are communicating with the 
user, his locale tells you what language he speaks). It makes much less 
sense for file IO.


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