Hi Michael,

Thanks for this explanation, really interesting to me. I actually never had
the occasion to use fn:fold-left/right functions. Probably because Ibm
sticked with XSLT 2 and discover XSLT 3 features step by step.
Ibll definitely have a look to this lower level primitive, Ibll need to
change my mind using maps and array which is not yet natural to me :)

By the way, I see a lot questions about grouping here, thatbs why I shared
this lib and approach.
This was the first time I used high order function in this balmostb
generic grouping actually.

Cheers,
Matthieu