A persistent core.logic database. The goal of pldb is to provide core.logic fact/relation mechanism that doesn't use mutable namespace references. This makes it easier to use core.logic in multi-threaded environments like web applications.
Relations are defined in the same way as core.logic relations. These relations are bound to the namespace they are defined in, as in core.logic.
(pldb/db-rel man p)
(pldb/db-rel woman p)
(pldb/db-rel likes p1 p2)
(pldb/db-rel fun p)Facts are persistent values. They can be created using db-facts, extending the current db context.
(def facts
(pldb/db-facts
[man 'Bob]
[man 'John]
[man 'Ricky]
[woman 'Mary]
[woman 'Martha]
[woman 'Lucy]
[likes 'Bob 'Mary]
[likes 'John 'Martha]
[likes 'Ricky 'Lucy]))Or they can be created from a given base database using db-fact.
(def facts
(-> pldb/empty-db
(pldb/db-fact man 'Bob)
(pldb/db-fact man 'John)
(pldb/db-fact man 'Ricky)
(pldb/db-fact woman 'Mary)
(pldb/db-fact woman 'Martha)
(pldb/db-fact woman 'Lucy)
(pldb/db-fact likes 'Bob 'Mary)
(pldb/db-fact likes 'John 'Martha)
(pldb/db-fact likes 'Ricky 'Lucy)))To run a query with a given database, use with-db.
(pldb/with-db facts
(run* [q]
(fresh [x y]
(likes x y)
(fun y)
(== q [x y]))))- multiple arity relations are not supported yet
- indexing is not implemented yet
- retractions are not implemented yet
Copyright © 2013 ThreatGRID Inc.
Distributed under the Eclipse Public License, the same as Clojure.