Mandarax is a rule compiler combining OOP and logic programming concepts, creating systems with built-in provenance (deprecated).
This project is not longer maintained !
To get an idea about how this works, try the userv sample application. The UI can be started with org.mandarax.examples.userv.app.Main. This is based on business rules
defining relations (defined in src/main/java/org/mandarax/examples/userv/rules) which are compiled into Java classes (src/main/java/org/mandarax/examples/userv/rules/generated) by the mandarax compiler org.mandarax.compiler.impl.DefaultCompiler.
The generated classes provide a straight-forward API to query the relations (with their semantics defined by external data sources, derivation rules, or some other means). For instance
org.mandarax.examples.userv.rules.generated.BasePremiumRelInstances defines ResultSet<BasePremiumRel> getPremium (Car car). The result set is a DB (JDBC) - like
iterator, but also contains an API List<DerivationLogEntry> getDerivationLog() to provide provenance, i.e. the rules and data used to compute a particular result.