Hello Einar, Thursday, April 20, 2006, 6:24:14 PM, you wrote:
Does Data.CharEncoding work with encodings that have state associated with them? One example is ISO-2022-JP.
no. so the list of things that is principal impossible with current design of Data.CharEncoding is error processing/masking and handling of stateful encodings
Maybe with using a suitable monad transformer?
how you imagine that? we have the following classes: class ByteStream m h where vGetByte :: h -> m Word8 vPutByte :: h -> Word8 -> m () class TextStream m h where vGetChar :: h -> m Char vPutChar :: h -> Char -> m () and char encoding transformer should implement later via former: instance ByteStream m h => TextStream m (CharEncoding h) where ... it seems that we should just improve type of (vGetByte->vGetChar) and (vPutByte->vPutChar) converters so that they will accept old state and error processing mode and returns error code and new state. smth like this: type PutByte m h = h -> Word8 -> m () type EncodeConverter m h state = PutByte m h -> ErrMode -> h -> state -> m (Either Char ErrCode, state) where `state` saves current processing state, Errmode is error processing mode and ErrCode is error code. of course, this should make implementation even slower :(
2) Einar once asked me about changing the encoding on the fly, that is needed for some HTML processing. it is also possible that some program will need to intersperse text I/O with buffer/array/byte/bits I/O. it's a sort of things that are absolutely impossible with iconv
The example goes like this: 1) HTTP client reads response from server using ascii 2) When reading headers is complete, either: * decode body (binary data) and after decompressing convert to text * decode body (text in some encoding) straight from the Handle.
Is there a reason this is impossible with iconv if the character conversion is on top of the buffering?
let's they answer :) i just want to mention to Simon that some apps want to use binary and text i/o at the same stream. if you think that HTTP has bad design, you know where to complain ;) -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com