Author here: very happy to see some interest in microKanren. It's such a lovely little gem. Has anyone used microKanren as part of a production program?
Not really production, but probably THE most impressive biomedicine research work I've seen (and I'm an academic MD):
https://github.com/webyrd/mediKanren
This is a FOL theorem prover that uses medical research articles as terms. They use it to do genetics and drug repurposing metaresearch. It's like the wet dream of all the biomed machine learning fanboys out there, except that:
1. it's not machine learning
and
2. it really works
Note you can do machine learning of logic programs. My PhD research:
https://github.com/stassa/louise
In which case it _is_ machine learning and it still really works :D