Programming language CLIPS

CLIPS was created and was maintained by NASA (Software Technology Branch, Johnson Space Center). It has been used for the development of numerous knowledge based applications. It is a production system language with a rule base and a working memory (database of facts and instances). Rules consists of three parts: The condition part consists of a number of conditional elements. All these elements must be satisfied by the current state of the database in order to activate a rule. The action part consists of an ordered sequence of actions. Every rule has the following form
(defrule <rule name>
(declare ( ... )) - declaration part
... - condition part
=>
... - action part
)
In addition to the rule based programming, CLIPS enables the use of object oriented and functional programming. More information about CLIPS can be found here.