samuell / clara-rules

Forward-chaining rules in Clojure

About

Clara is a forward-chaining rules engine written in Clojure with Java interoperability. It aims to simplify code with a developer-centric approach to expert systems. See clara-rules.org for more.

Usage

Here's a simple example. Complete documentation is at clara-rules.org.

(ns clara.support-example
  (:require [clara.rules :refer :all]))

(defrecord SupportRequest [client level])

(defrecord ClientRepresentative [name client])

(defrule is-important
  "Find important support requests."
  [SupportRequest (= :high level)]
  =>
  (println "High support requested!"))

(defrule notify-client-rep
  "Find the client representative and send a notification of a support request."
  [SupportRequest (= ?client client)]
  [ClientRepresentative (= ?client client) (= ?name name)] ; Join via the ?client binding.
  =>
  (println "Notify" ?name "that"  ?client "has a new support request!"))

;; Run the rules! We can just use Clojure's threading macro to wire things up.
(-> (mk-session)
    (insert (->ClientRepresentative "Alice" "Acme")
            (->SupportRequest "Acme" :high))
    (fire-rules))

;;;; Prints this:

;; High support requested!
;; Notify Alice that Acme has a new support request!

Building

Clara is built, tested, and deployed using Leiningen.

Availability

Clara releases are on Clojars. Simply add the following to your project:

Communication

Questions can be posted to the Clara Rules Google Group or the Slack channel.

Contributing

See CONTRIBUTING.md

LICENSE

Copyright 2018 Cerner Innovation, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.