(defdetunipred <name > <num args > <unifier1 unifier2 >
<aux-vars > <body >)
defdetunipred
is used when the defined predicate needs to unify values with arguments (or unify in general). The body is executed and, if successful, (that is,
detpred-fail
has not been called) unification is performed on the two unifiers. (If more than two items need to be unified, cons up lists of items to unify).
(defdetunipred my-arg 3 (temp1 temp2)
(temp1 temp2 index term value)
(setf index (special-arg 0)
term (special-arg 1)
value (special-arg 2))
(unless (and (numberp index)
(plusp index)
(or (and (term-p term)
(< index (length term)))
(and (consp term)
(< index 3))))
(detpred-fail my-arg 3))
(if (consp term)
(setf temp1 (if (= index 1)
(car term)
(cdr term)))
(setf temp1 (term-ref term index)))
(setf temp2 value))