— Function: caddr x

This function is equivalent to (car (cdr (cdr x))). Likewise, this package defines all 28 cxxxr functions where xxx is up to four ‘a’s and/or ‘d’s. All of these functions are setf-able, and calls to them are expanded inline by the byte-compiler for maximum efficiency.

— Function: first x

This function is a synonym for (car x). Likewise, the functions second, third, ..., through tenth return the given element of the list x.

— Function: rest x

This function is a synonym for (cdr x).

— Function: endp x

Common Lisp defines this function to act like null, but signaling an error if x is neither a nil nor a cons cell. This package simply defines endp as a synonym for null.

— Function: list-length x

This function returns the length of list x, exactly like (length x), except that if x is a circular list (where the cdr-chain forms a loop rather than terminating with nil), this function returns nil. (The regular length function would get stuck if given a circular list.)

— Function: list* arg &rest others

This function constructs a list of its arguments. The final argument becomes the cdr of the last cell constructed. Thus, (list* a b c) is equivalent to (cons a (cons b c)), and (list* a b nil) is equivalent to (list a b).

(Note that this function really is called list* in Common Lisp; it is not a name invented for this package like member* or defun*.)

— Function: ldiff list sublist

If sublist is a sublist of list, i.e., is eq to one of the cons cells of list, then this function returns a copy of the part of list up to but not including sublist. For example, (ldiff x (cddr x)) returns the first two elements of the list x. The result is a copy; the original list is not modified. If sublist is not a sublist of list, a copy of the entire list is returned.

— Function: copy-list list

This function returns a copy of the list list. It copies dotted lists like (1 2 . 3) correctly.

— Function: copy-tree x &optional vecp

This function returns a copy of the tree of cons cells x. Unlike copy-sequence (and its alias copy-list), which copies only along the cdr direction, this function copies (recursively) along both the car and the cdr directions. If x is not a cons cell, the function simply returns x unchanged. If the optional vecp argument is true, this function copies vectors (recursively) as well as cons cells.

— Function: tree-equal x y &key :test :test-not :key

This function compares two trees of cons cells. If x and y are both cons cells, their cars and cdrs are compared recursively. If neither x nor y is a cons cell, they are compared by eql, or according to the specified test. The :key function, if specified, is applied to the elements of both trees. See Sequences.