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Re: [Scheme-reports] (read|write)-char [was Opinion about R7RS]
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On 07/14/2012 04:04 PM, Arthur A. Gleckler wrote:
> On Wed, Jul 11, 2012 at 2:57 PM, Jean-Michel HUFFLEN
>> Let us go back to characters. You do not want to give any
>> priviledge to a particular encoding. OK. How can I write
>> portable code, running on several interpreters? Some characters
>> may be not included in the encoding used for writing characters.
>> How can I make sure that I will avoid errors? For me, if I had: -
>> a function returning the default encoding used, - a function
>> returning the available encodings, I would be the happiest
> I like the idea, but that's exactly the kind of thing that should
> be in the larger Scheme specified by working group two, not in the
> smaller Scheme standard we're working on at the moment. Things
> like first-class representations for character encodings are like
> yarn -- if you keep pulling, eventually the whole sweater is
It seems to me that we should not be thinking about the encoding
of characters, regardless of small or large lang, until it is
time to do I/O.
While processing strings with scheme code, it is sufficient to
consider a string as a sequence of characters. If you are worried
about the encoding, it's because you're doing something that does not
use the string as a sequence of characters, like being worried about
the layout of bits in bignums.
It is at the interfaces to the outside world that encoding becomes
important; when we have a bunch of bits that we've read from a binary
port and we want to convert it into a string value, or when we have
to write a string that something which reads in a particular encoding
will understand, or etc.
That said, it is reasonable to wish for a way of knowing whether a
particular character is in the repertoire that can be encoded/decoded
by an encoding.
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