[Haskell] HaXml ANYContent

Georg Martius mai99dgf at studserv.uni-leipzig.de
Wed Aug 10 20:49:49 EDT 2005


I have some problems with the ANYContent type in HaXml. 
Currently (1.13) ANYContent is defined as 
data ANYContent = ANYContent
which means I cannot store anything in there. 
I need two things:
1) Parse a file where some elements have ANY content, but be able to use the 
2) Create a data structure and fill the ANYContent field and be able to write 
that to an XML file.

I suggest the following sollution:
> newtype Unparsed =  Unparsed String
> data ANYContent = forall a . XmlContent a => Either UnParsed (ANYContent a)

If an XML file is parsed we don't know the type yet. Therefore we put 
everything in Unparsed field. Later on one can use a Parser on that 
explicitly. It would also make the roundtrip XML->Haskell ->XML more stable.

---- Georg Martius,  Tel: (+49 34297) 89434 ----
------- http://www.flexman.homeip.net ---------

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