If you think that's crazy, check out https://www.infoq.com/presentations/miniKanren https://www.infoq.com/presentations/miniKanren at the 31:30 mark. These two

If you think that's crazy, check out https://www.infoq.com/presentations/miniKanren https://www.infoq.com/presentations/miniKanren at the 31:30 mark. These two guys teach their logic programming system a subset of scheme, then they can run it "backwards" to find quines - programs that evaluate to themselves.