CODEWITHSUNDEEP
clips
grandrew
grandrew

Reputation: 738

CLIPS match first field of a pattern

I am trying to retract all facts of form:

(<something> task-error)

To do this I wrote the rule:

(defrule retract-task-error "retract task error"
         (declare (salience -1000))
         ?f <- (?n task-error)
         =>
         (retract ?f)
)

But it does not work with error:

[PRNTUTIL2] Syntax Error:  Check appropriate syntax for the first field of a pattern.

Is it ever possible to accomplish this task with CLIPS or do I need a code rearrangement to avoid matching first fields of facts?

Upvotes: 1

Views: 834

Answers (1)

Gary Riley
Gary Riley

Reputation: 10757

The first field of a pattern must be a symbol. The simplest solution would probably be adding a common symbol (such as task) to the beginning of all facts and patterns which can contain task-error: 

(defrule retract-task-error "retract task error"
         (declare (salience -1000))
         ?f <- (task ?n task-error)
         =>
         (retract ?f)
)

Upvotes: 2

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