- (define-predicate variable)syntax
Returns: undefined
Defines variable to be an operation which, by default, returns false.
(define-predicate var) ==> (define-operation (var obj) #f)
The intent is that particular OBJECT-expressions contain clauses of the form ((variable SELF) #t). This way the operation defined by DEFINE-PREDICATE may act as a type predicate that returns true only for those objects returned by such OBJECT-expressions.