function—a designator for a function that must take as many arguments as there are lists.
list—a proper list.
list-1—the first list (which must be a proper list).
result-list—a list.
concatenated-results—a list.
The mapping operation involves applying function to
successive sets of arguments in which
one argument is obtained from each sequence.
Except for mapc and mapl,
the result contains the results returned by function.
In the cases of mapc and mapl,
the resulting sequence is list.
function is called
first on all the elements with index 0, then on all those
with index 1, and so on.
result-type specifies the type of
the
resulting sequence.
If function is a symbol, it is coerced
to a function as if by symbol-function.
mapcar operates on successive elements of the lists.
function is applied to the first element of each list,
then to the second element of each list, and so on.
The iteration terminates when the shortest list runs out,
and excess elements in other lists are ignored.
The value returned by mapcar is a list
of the results of successive calls to function.
mapc is like mapcar except that the results of
applying function are not accumulated.
The list argument is returned.
maplist is like mapcar except that
function is applied to successive sublists of the lists.
function
is first applied to the lists themselves,
and then to the cdr of each
list, and then to the cdr of the cdr
of each list, and so on.
mapl is like maplist except that the results of
applying function are not accumulated;
list-1 is returned.
mapcan and mapcon are like mapcar and
maplist respectively, except that the results of
applying function are combined
into a list by the use of nconc
rather than list.
That is,
(mapcon f x1 ... xn) ≡ (apply #'nconc (maplist f x1 ... xn))
and similarly for the relationship between mapcan
and mapcar.
(mapcar #'car '((1 a) (2 b) (3 c))) → (1 2 3) (mapcar #'abs '(3 -4 2 -5 -6)) → (3 4 2 5 6) (mapcar #'cons '(a b c) '(1 2 3)) → ((A . 1) (B . 2) (C . 3)) (maplist #'append '(1 2 3 4) '(1 2) '(1 2 3)) → ((1 2 3 4 1 2 1 2 3) (2 3 4 2 2 3)) (maplist #'(lambda (x) (cons 'foo x)) '(a b c d)) → ((FOO A B C D) (FOO B C D) (FOO C D) (FOO D)) (maplist #'(lambda (x) (if (member (car x) (cdr x)) 0 1)) '(a b a c d b c)) → (0 0 1 0 1 1 1) ;An entry is 1 if the corresponding element of the input ; list was the last instance of that element in the input list. (setq dummy nil) → NIL (mapc #'(lambda (&rest x) (setq dummy (append dummy x))) '(1 2 3 4) '(a b c d e) '(x y z)) → (1 2 3 4) dummy → (1 A X 2 B Y 3 C Z) (setq dummy nil) → NIL (mapl #'(lambda (x) (push x dummy)) '(1 2 3 4)) → (1 2 3 4) dummy → ((4) (3 4) (2 3 4) (1 2 3 4)) (mapcan #'(lambda (x y) (if (null x) nil (list x y))) '(nil nil nil d e) '(1 2 3 4 5 6)) → (D 4 E 5) (mapcan #'(lambda (x) (and (numberp x) (list x))) '(a 1 b c 3 4 d 5)) → (1 3 4 5)
In this case the function serves as a filter;
this is a standard Lisp idiom using mapcan.
(mapcon #'list '(1 2 3 4)) → ((1 2 3 4) (2 3 4) (3 4) (4))
Should be prepared to signal an error of type type-error if
any list is not a proper list.