This is how I did it using the HXT library :
Prelude Text.XML.HXT.Parser.XmlParsec Text.XML.HXT.Arrow.XmlIOStateArrow
Text.XML.HXT.Arrow> runX (readString [] "<tag>123</tag>" >>> getXPathTrees
"tag" >>> getChildren >>> getText)
["123"]
Everything after "Prelude" upto the first ">" is what you have to import to
make this work.
-"readString" converts the input string into a internal representation of an
XML tree
-"getXPathTrees" sets the path to all <tag>'s,
-"getChildren" narrows it down to the data between <tag> and </tag>,
-"getText" extracts all the data between those tags,
-"runX" fires up the whole process and returns the results as a list in the
IO Monad.
hth,
deech
On Tue, Sep 29, 2009 at 2:25 PM, Robert Ziemba
I have been working with the regular expression package (Text.Regex.Posix). My hope was to find a simple way to remove a pair of XML tags from a short string.
I have something like this "<tag>Data</tag>" and would like to extract 'Data'. There is only one tag pair, no nesting, and I know exactly what the tag is.
My first attempt was this:
"<tag>123</tag>" =~ "[^<tag>].+[^</tag>]"::String
result: "123"
Upon further experimenting I realized that it only works with more than 2 digits in 'Data'. I occured to me that my thinking on how this regular expression works was not correct - but I don't understand why it works at all for 3 or more digits.
Can anyone help me understand this result and perhaps suggest another strategy? Thank you.
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