Any ideas?

It may be related to the fact that maps don’t have defined iteration orders - you should be able to call

.asIterable()

or

.asSequence()

and perform your reduction on that instead

the syntax was just to ilustrate the idea, thanks for the info!!

@Rruiz You can fold maps with Arrow both in a left and and right associative fashion https://arrow-kt.io/docs/apidocs/arrow-extras/arrow.data/-map-k/index.html

thanks Raul, I'll give it a try!

@Rruiz sounds good, if you run into any issues we are here to help.