Hello café, 

I have seen tutorials about extracting information from a tag soup, but I have a different use case:
I want to read a xml file, find a tag, change its content, and write the xml file back.

This is an example of the files

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<idPkg:Story xmlns:idPkg="http://ns.adobe.com/AdobeInDesign/idml/1.0/packaging" DOMVersion="7.0">
       <Story Self="ub9fad" AppliedTOCStyle="n" TrackChanges="false" StoryTitle="$ID/" AppliedNamedGrid="n">
               <StoryPreference OpticalMarginAlignment="false" OpticalMarginSize="12" FrameType="TextFrameType" StoryOrientation="Horizontal" StoryDirection="LeftToRightDirection"/>
               <InCopyExportOption IncludeGraphicProxies="true" IncludeAllResources="false"/>
               <ParagraphStyleRange AppliedParagraphStyle="ParagraphStyle/prix">
                       <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/$ID/[No character style]">
                               <Content>zzznba5</Content>
                       </CharacterStyleRange>
               </ParagraphStyleRange>
       </Story>
</idPkg:Story>

Assuming I want to change the content of the "Content" tag, this is what I came up with (simplified), I'm using direct recursion. Is there a better way ?

ts = do
 soup <- parseTags `fmap` readFile "idml/h00/Stories/Story_ub9fad.xml"
 writeFile "test" $ renderTagsOptions renderOptions{optMinimize = const True}
                  $ modif soup

modif [] = []
modif (x@(TagOpen "Content" []):TagText _m : xs) = x : TagText "modified" : modif xs
modif (x:xs) = x : modif xs

David.