folding xml - reprise

[Catonano]

Hi,

I'm trying to do something like a fold, but over a tree instead of a list. Is there anything like that?

If it's unclear what I mean, there's a mechanism like that in guile:
https://www.gnu.org/software/guile/manual/html_node/SXML-Tree-Fold.html

They use it e.g. for XML transformations, but it's really a generic operation and quite useful.

Here's a paper on it by Andy Wingo if anyone wants to know the theory behind:

https://pdfs.semanticscholar.org/d41a/175cf5bf19c795b940edf566988df05ee4a1.pdf

is there anything along those lines in Racket ?

Thanks in advance