(loop for (arg next) on args
while next
do
- (let ((lvar-type (lvar-type arg)))
- (unless (or (csubtypep list-type lvar-type)
- (csubtypep lvar-type list-type)
- ;; Check for NIL specifically, because
- ;; SYMBOL or ATOM won't satisfie the above
- (csubtypep null-type lvar-type))
- (assert-lvar-type arg list-type
- (lexenv-policy *lexenv*))
- (return *empty-type*))))
+ (when (eq (type-intersection (lvar-type arg) list-type)
+ *empty-type*)
+ (assert-lvar-type arg list-type
+ (lexenv-policy *lexenv*))
+ (return *empty-type*)))
(loop with all-nil = t
for (arg next) on args
for lvar-type = (lvar-type arg)
do
(cond
;; Cons in the middle guarantees the result will be a cons
- ((csubtypep lvar-type cons-type)
+ ((not (csubtypep null-type lvar-type))
(return cons-type))
;; If all but the last are NIL the type of the last arg
;; can be used