[Haskell-cafe] Children elements with HXT
Max Cantor
mxcantor at gmail.com
Wed Dec 23 04:20:32 EST 2009
That stuffed me up for a bit. I wrote some ugly template haskell a while back to automatically generate XmlPickler instances. can send to you if you want
On Dec 23, 2009, at 7:55 AM, Tony Morris wrote:
> Adding (a_remove_whitespace,v_1) as a parser option when running solves
> it. Silly me.
>
>
> Tony Morris wrote:
>> I am trying to parse XML using HXT following
>> http://www.haskell.org/haskellwiki/HXT/Conversion_of_Haskell_data_from/to_XML
>>
>> Here is my XML file (way.xml):
>>
>> <way id="27776903" visible="true" timestamp="2009-05-31T13:39:15Z"
>> version="3" changeset="1368552" user="Matt" uid="70">
>> <tag k="access" v="private"/>
>> <tag k="highway" v="service"/>
>> </way>
>>
>> The problem is when parsing, by reading the <tag> entries into the
>> list held by the Way data structure, I cannot get anything but an
>> empty list.
>>
>> Here is my parsing code:
>>
>> import Text.XML.HXT.Arrow
>>
>> newtype Way = Way {
>> tags :: [Tag]
>> } deriving (Eq, Show)
>>
>> xpWay :: PU Way
>> xpWay = xpElem "way" (xpWrap (Way, tags) (xpList xpTag))
>>
>> data Tag = Tag {
>> k :: String,
>> v :: String
>> } deriving (Eq, Show)
>>
>> xpTag :: PU Tag
>> xpTag = xpElem "tag" (xpWrap (uncurry Tag, k &&& v) (xpPair (xpAttr
>> "k" xpText) (xpAttr "v" xpText)))
>>
>> When I run, I get the following result:
>>
>> Main> run = runX (xunpickleDocument xpWay [] "way.xml")
>> [Way {tags = []}]
>>
>> Why is the tags list empty instead of holding two entries?
>>
>>
>>
>
> --
> Tony Morris
> http://tmorris.net/
>
>
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