The procedures in this section test specific properties of lists.
Return #t if obj is a proper list, or #f
otherwise. This is the same as the core list? (see List Predicates).
A proper list is a list which ends with the empty list () in
the usual way. The empty list () itself is a proper list too.
(proper-list? '(1 2 3)) ⇒ #t (proper-list? '()) ⇒ #t
Return #t if obj is a circular list, or #f
otherwise.
A circular list is a list where at some point the cdr refers
back to a previous pair in the list (either the start or some later
point), so that following the cdrs takes you around in a
circle, with no end.
(define x (list 1 2 3 4)) (set-cdr! (last-pair x) (cddr x)) x ⇒ (1 2 3 4 3 4 3 4 ...) (circular-list? x) ⇒ #t
Return #t if obj is a dotted list, or #f
otherwise.
A dotted list is a list where the cdr of the last pair is not
the empty list (). Any non-pair obj is also considered a
dotted list, with length zero.
(dotted-list? '(1 2 . 3)) ⇒ #t (dotted-list? 99) ⇒ #t
It will be noted that any Scheme object passes exactly one of the
above three tests proper-list?, circular-list? and
dotted-list?. Non-lists are dotted-list?, finite lists
are either proper-list? or dotted-list?, and infinite
lists are circular-list?.
Return #t if lst is the empty list (), #f
otherwise. If something else than a proper or circular list is passed
as lst, an error is signaled. This procedure is recommended
for checking for the end of a list in contexts where dotted lists are
not allowed.
Return #t is obj is not a pair, #f otherwise.
This is shorthand notation (not (pair? obj)) and is
supposed to be used for end-of-list checking in contexts where dotted
lists are allowed.
Return #t if all argument lists are equal, #f otherwise.
List equality is determined by testing whether all lists have the same
length and the corresponding elements are equal in the sense of the
equality predicate elt=. If no or only one list is given,
#t is returned.