Jess (programming language)

<h2 id="license">License</h2>
<p>The <a href="/facts/Software_license/7enfIqhL">licensing</a> for Jess is <a href="/facts/Freeware/c8oGA9ju">freeware</a> for education and government use, and is <a href="/facts/Proprietary_software/9zcskxYL">proprietary software</a>, needing a license, for commercial use. In contrast, CLIPS, which is the basis and starting code for Jess, is <a href="/facts/Free_and_open-source_software/1cHtjLCB">free and open-source software</a>.
</p>
<h2 id="code-examples">Code examples</h2>
<p>Code examples:
</p>
; is a comment

(bind ?x 100)

; x = 100

(deffunction max (?a ?b)
             (if (> ?a ?b) then ?a else ?b))

(deffacts myroom
          (furniture chair)
          (furniture table)
          (furniture bed)
          )

(deftemplate car
             (slot color)
             (slot mileage)
             (slot value)
             )

(assert (car (color red) (mileage 10000) (value 400)))

<p>Sample code:
</p>
(clear)
(deftemplate blood-donor (slot name) (slot type))
(deffacts blood-bank ; put names & their types into [[working memory]]
          (blood-donor (name "Alice")(type "A"))
          (blood-donor (name "Agatha")(type "A"))
          (blood-donor (name "Bob")(type "B"))
          (blood-donor (name "Barbara")(type "B"))
          (blood-donor (name "Jess")(type "AB"))
          (blood-donor (name "Karen")(type "AB"))
          (blood-donor (name "Onan")(type "O"))
          (blood-donor (name "Osbert")(type "O"))
          )
(defrule can-give-to-same-type-but-not-self ; handles A > A, B > B, O > O, AB > AB, but not N1 > N1
         (blood-donor (name ?name)(type ?type))
         (blood-donor (name ?name2)(type ?type2 &:(eq ?type ?type2) &: (neq ?name ?name2) ))
         =>
         (printout t ?name " can give blood to " ?name2 crlf)
         )
(defrule O-gives-to-others-but-not-itself ; O to O cover in above rule
         (blood-donor (name ?name)(type ?type &:(eq ?type "O")))
         (blood-donor (name ?name2)(type ?type2 &: (neq ?type ?type2) &: (neq ?name ?name2) ))
         =>
         (printout t ?name " can give blood to " ?name2 crlf)
         )
(defrule A-or-B-gives-to-AB ; case O gives to AB and AB gives to AB already dealt with
         (blood-donor (name ?name)(type ?type &:(or (eq ?type "A") (eq ?type "B" ))))
         (blood-donor (name ?name2)(type ?type2 &: (eq ?type2 "AB") &: (neq ?name ?name2) ))
         =>
         (printout t ?name " can give blood to " ?name2 crlf)
         )
;(watch all)
(reset)
(run)

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Semantic_reasoner/rXkm48cY">Semantic reasoner</a></li>
<li><a href="/facts/Decision_Model_and_Notation/9hynaRd6">Decision Model and Notation</a></li></ul>
<h3>Related systems</h3>
<ul><li><a href="/facts/CLIPS/5Sek388z">CLIPS</a>: <a href="/facts/Public-domain_software/LUpdqQXQ">public-domain software</a> tool to build expert systems</li>
<li><a href="/facts/ILOG/smnFvLJz">ILOG</a> rules: business rule management system</li>
<li>JBoss <a href="/facts/Drools/wNSpDqDk">Drools</a>: business rule management system (BRMS)</li>
<li><a href="/facts/Prolog/r5h66Qh1">Prolog</a>: general purpose logic programming language</li>
<li><a href="/facts/OpenL_Tablets/R7gPNNHr">OpenL Tablets</a>: business centric rules and BRMS</li>
<li>DTRules: <a href="/facts/Decision_table/KbWcbltC">decision table</a> based, open-source rule engine for Java</li></ul>

<h3>Further sources</h3>
<ul><li>Friedman-Hill, Ernest (2003). <a href="https://books.google.com/books?id=-xxjRZhyF0IC&q=Jess+in+Action:+Rule+Based+Systems+in+Java"><i>Jess in Action: Rule Based Systems in Java</i></a>. Manning Publications. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 9781930110892. Retrieved March 30, 2012. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 1-930110-89-8</li></ul>
<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.jessrules.com">Official website</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Hemmer, Markus C. (2008). Expert Systems in Chemistry Research. CRC Press. pp. 47–48. ISBN 9781420053241. Retrieved March 30, 2012. ISBN 978-1-4200-5323-4 <a href="9781420053241" target="_blank">9781420053241</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Hemmer, Markus C. (2008). Expert Systems in Chemistry Research. CRC Press. pp. 47–48. ISBN 9781420053241. Retrieved March 30, 2012. ISBN 978-1-4200-5323-4 <a href="9781420053241" target="_blank">9781420053241</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Hemmer, Markus C. (2008). Expert Systems in Chemistry Research. CRC Press. pp. 47–48. ISBN 9781420053241. Retrieved March 30, 2012. ISBN 978-1-4200-5323-4 <a href="9781420053241" target="_blank">9781420053241</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Hemmer, Markus C. (2008). Expert Systems in Chemistry Research. CRC Press. pp. 47–48. ISBN 9781420053241. Retrieved March 30, 2012. ISBN 978-1-4200-5323-4 <a href="9781420053241" target="_blank">9781420053241</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Hemmer, Markus C. (2008). Expert Systems in Chemistry Research. CRC Press. pp. 47–48. ISBN 9781420053241. Retrieved March 30, 2012. ISBN 978-1-4200-5323-4 <a href="9781420053241" target="_blank">9781420053241</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

Jess (programming language) open-in-new

Jess (programming language)