Followup: You have a Dtd2Haskell tool, but DTDs are very inexpressive and the result is string based types. Is there a tool for converting e.g. relaxNG into haskell types? Then we get direct support for e.g. doubles or URLs. I know there is a relaxNG validator written in haskell, but that is not the same thing... -Alex- http://www.thaiopensource.com/relaxng/derivative.html On Thu, 28 Oct 2004, Malcolm Wallace wrote:
"S. Alexander Jacobson" <alex@alexjacobson.com> writes:
Is there a good entry point into HaXml? I've now spent some time trying to understand it and feel like I've gotten nowhere.
It is a large package with many diverse facilities, so I'm not surprised. I take it you have read the ICFP'99 paper linked to from the HaXml webpage? To give a fuller answer, it would be helpful to know more about your specific XML needs.
The Haddock documentation enumerates what each function does, but I still don't know how to produce a valid XML document?
Where does your document come from? Has it been parsed already, then manipulated, and you want to spit it out again? Or are you trying to generate a fresh document from nothing? Or perhaps you have some existing Haskell data-structure you want to convert to XML for external representation only?
For example, this is obviously the wrong way to go:
simp2 = document $ Document (Prolog Nothing [] Nothing []) [] $ Elem "root" [("attr",AttValue [Left "v\"al"])] [CString False "<<<<<>>&&&"]
Because, it produces the obviously wrong:
<root attr="v"al"><<<<<>>&&&</root>
Ah. Escaping of special characters within text is a separate issue. It need only be done once, just before output. See Text.XML.HaXml.Escape - specifically you want something like
simp2 = document $ Document (Prolog Nothing [] Nothing []) [] $ xmlEscape stdXmlEscaper $ Elem "root" [("attr",AttValue [Left "v\"al"])] [CString False "<<<<<>>&&&"]
I assume/hope that the combinators properly encode/escape attribute values and CDATA,
No, at the moment they don't. You can always do it one-shot at the end, as in the example above, although it would probably be better from a correctness point of view if the combinators did as you suggest.
And once I've done so, is there a way to put PIs in via the combinators
Currently, there are no combinators specifically for generating PIs (simply because no-one has asked for them before), but it would be extremely easy to add. For instance:
mkPI :: String -> String -> CFilter mkPI pitarget str = \t-> [ CMisc (PI (pitarget,str)) ]
Regards, Malcolm
______________________________________________________________ S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com