Minikanren (and core.logic) is very fun to explore. It's such a brain bender and it seems well suited for some PL things. E.g. say you have some custom interpre

Minikanren (and core.logic) is very fun to explore. It's such a brain bender and it seems well suited for some PL things. E.g. say you have some custom interpreter. If you implement that interpreter in Minikanren, you can run it backwards and answer the question "what program, if any, evaluates to this result". To generate a quine, you make both the input and the output of the interpreter the same logic var, and have Minikanren solve for it. On the other hand, I was unable to find a use for it any real world problems (in my case: scheduling and portfolio optimization). I always use a linear constraint solver instead.