:UNBOUNDP

Purpose

Checks whether a variable does not have a binding.

  ((:BIND ?x 1)
   (:FAIL (:UNBOUNDP ?x))
   (:PRINTLN "?x is bound"))

  ((:UNBOUNDP ?y)
   (:PRINTLN "?y is not bound"))

Succeeds if the given variable is not bound.

Fails if the variable is bound.

None.