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<section class="intro">
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      <p class="first">Retaking rules for developers</p>
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<section class="features">
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    Rules can greatly simplify business logic, but often come in the form of limited mini-languages and complex tools. Let's take them back.
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<section class="features">
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    <h2>Simple</h2>
    <p>
      Clara offers a simpler way to express domain knowledge in code, without the weight of an enterprise rule system.
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      <h2>Expressive</h2>
      <p>
        Simple rules stay simple, but users can write rich logic or invoke external libraries when they need to.
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    <h2>It's just Clojure</h2>
    <p>Rules are just Clojure code, and can be managed and reused like anything else.</p>
{% highlight clojure %}
(defrule work-approval
  "Check order approval."
  [WorkOrder (= type :repair)
             (= ?order-id order-id)]
  [:not [ApprovalForm (= ?order-id approved-id)
                      (= formname "27B-6")]]
  =>
  (insert! (->MissingApproval ?id "No 27B-6.")))

{% endhighlight %}
    Check out the <a href="/docs/firststeps/">developer guide</a>.
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    <h2>Easily used from Java</h2>
    <p>Just include your rules as a resource and use Java Beans or Clojure records as facts.</p>
{% highlight java %}
List<QueryResult> results =
  RuleLoader.loadRules("clara.examples")
    .insert(facts)
    .fireRules()
    .query("clara.examples/approvals");

for (QueryResult result: results)
  System.out.println(result.getResult("?id"));
{% endhighlight %}
    See the <a href="/docs/java/">Java documentation for more</a>.
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    <h2>Drawn from multiple worlds</h2>
    <p>
      Clara aims to combine the best ideas from expert systems, functional programming, and the best known develpment practices.
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    <p>
      <a href="/docs/approach/">Learn more about Clara's approach</a>.
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    <h2>And many other features...</h2>
    <p>Clara supports the features you'd expect from a rule engine, such as support for <a href="/docs/truthmaint">truth maintenance</a>,
      <a href="/docs/durability">durability</a>,
      <a href="/docs/inspection">rule activation explanations</a>, <a href="/docs/accumulators">accumulators to reason across sets of facts</a>,
      and others.
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  <span class="take-action"><a href="/docs/firststeps/">Get Started</a></span>

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