It looks like you need to add a “catch all” clause for non map objects. If the m/cata fails, so will the whole clause. Add

?x ?x

Also, you can write

(m/and :foo ?tag)

(m/pred #(= % :foo) ?tag)

ah sweet, let me give this a try. still figuring stuff out, but this is really cool s@#$ lol.

ok, ugh, that didn’t work. it seems to just return the input unchanged

(def x (xml/parse-str "<foo><bar><baz>The baz value</baz></bar></foo>"))
  (def convert-foobar
    (m*/rewrite
      {:tag     (m/and :foo ?tag)
       :attrs    ?attrs
       :content [(m/cata !content) ...]}
      {:tag     (m/app (comp str/capitalize name) ?tag)
       :attrs    ?attrs
       :content [!content ...]}

      {:tag     (m/and :bar ?tag)
       :attrs    ?attrs
       :content [(m/cata !content) ...]}
      {:tag     (m/app (comp str/capitalize name) ?tag)
       :attrs    ?attrs
       :content [!content ...]}

      {:tag     (m/and :baz ?tag)
       :attrs    ?attrs
       :content [(m/cata !content) ...]}
      {:tag     (m/app (comp str/capitalize name) ?tag)
       :attrs    ?attrs
       :content [!content ...]}

      ?x ?x))

  (def convert-foobars
    (m*/bottom-up ; tried top-down, etc as well
      (m*/attempt convert-foobar)))

  (convert-foobars x)

@U380J7PAQ I took a minute to try this out on my local machine and would able to get it to work. The reason it was not rewriting was due to the :content [,,,] portion of the match, namely the [,,,]. Meander treats [,,,] and (,,,) as representing vectors and seqs respectively. In this case the value of :content is a seq so we have two options: use the (,,,) notation or use (m/seqable ,,,). In this case I might suggest using the latter:

(def convert-foobar
  (m*/rewrite
   {:tag     (m/and :foo ?tag)
    :attrs    ?attrs
    :content (m/seqable (m/cata !content) ...)}
   {:tag     (m/app (comp str/capitalize name) ?tag)
    :attrs    ?attrs
    :content (m/seqable !content ...)}

   {:tag     (m/and :bar ?tag)
    :attrs    ?attrs
    :content (m/seqable (m/cata !content) ...)}
   {:tag     (m/app (comp str/capitalize name) ?tag)
    :attrs    ?attrs
    :content (m/seqable !content ...)}

   {:tag     (m/and :baz ?tag)
    :attrs    ?attrs
    :content (m/seqable (m/cata !content) ...)}
   {:tag     (m/app (comp str/capitalize name) ?tag)
    :attrs    ?attrs
    :content (m/seqable !content ...)}

   ?x ?x))

Using your example input I was able get the output

{:tag "Foo",
 :attrs {},
 :content
 ({:tag :bar,
   :attrs {},
   :content ({:tag "Baz", :attrs {}, :content ("The baz value")})})}

Note you do not have to use m/seqable on the right, you can use the vector notation, etc.

ah hell it was just that? lol ok great thanks!

so another question on this. in my actual code, for some parent tags, there are possibly some children on the :content key, whose data I want to pull into the parent. and in those cases, I don’t want those children in the output so just in xml:

<foo>
   <param name="a" value="b"/>
   <bar>...</bar>
...
; converts to
<Foo a="b">
   <Bar>...<Bar>

You want to keep the <bar> and discard the <param>

I apologize, my previous message meant to have a question mark at the end of it. 😛

{:tag :foo 
 :content (m/seqable (m/or {:tag :bar :as !bar} _)}
{:tag "Foo"
 :content [{:tag "Bar" & !bar} ...]}

yes, i want to collect some info from params into Foo, then drop params

ok so I see how this one handles the omission of params, so that seems straightforward, so hmm I guess m/or can match on params use that in :attrs on the RHS, while the check on the RHS in content will keep the params out of the new :content. cool, gonna try that when i get back to my desk

Following up on this; how can I help?

Or, rather, do you still need some help?

hi, actually haven’t gotten to it yet today 🙂. thanks for checking in will let you know

No worries. Drop me a line whenever.