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Re: [Haskell-cafe] Children elements with HXT

Subject: Re: [Haskell-cafe] Children elements with HXT
From: Max Cantor
Date: Wed, 23 Dec 2009 17:20:32 +0800
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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