Difference between this and Logica?

[emummel20]

Hi quick question: Just discovered this project — What's the difference between Mangle and Logica?

Thanks.

[burakemir]

The purpose of Logica is to enable the use of datalog to query existing databases that support SQL. I believe it may also have a standalone interpreter meanwhile, but that was not why it was created. It really was made for big data analytics with datalog.

Instead, Mangle can be used as a go library. So one does not require an existing database as backend, but rather pulls in the data via golang code. It is possible to do simple integrations of existing databases if needed, which requires doing some development (concretely: implement a FactStore interface). The premise is that data exists in various forms and admits a "relational view" (or a "knowledge graph" view) of sorts, and we'd like to bring together multiple sources of data together to query them. This can happen now just by SQL queries but also by making rpc calls.

• Just like Mangle, Logic adds aggregation to datalog ("Logica = Logic with Aggregation").
• I believe Logica only supported bounded recursion in the beginning, but more recently now also supports unbounded recursion.
• I believe Logica does not support static type checking, whereas a Mangle program has to pass a type-checker before it can be run which catches mistakes. Not sure, though.
• Logica does not offer fully custom lattice-join (which is often just called "lattice support" in datalog implementations), but still offers a few built-in ways to do lattice-joins so it is possible to e.g. compute shortest paths also there.
• There are of course considerable syntax differences. Logica syntax enables aggregation through integrated rule syntax, whereas in Mangle, it is a bit more separate.
• Mangle has added back some top-down logic programming via defered predicates. Also, it is possible to extend Mangle with more "built-in" functions / predicates, though the APIs for that are all undocumented.

In terms of "paradigm", it is pretty similar. Does this help?

I have not looked in detail how Logica developed over time. It's a great idea and project that I have used at times. Translating datalog queries to SQL queries would technically be possible in Mangle, too, but not being worked on.