1.4.8 Lists
List functions can also be found in the sections on Association Lists, Sets, and Sequences.
| (cons x y) |
Creates a new pair containing x and y.
| (consp x) |
Returns true when x is a pair.
Examples: |
| > (consp nil) |
'() |
| > (consp 5) |
'() |
| > (consp "string") |
'() |
| > (consp (cons 1 nil)) |
't |
| > (consp '(1 2 3)) |
't |
| (append lst ...) |
Concatenates all the elements in the given lists into one list. This a macro
that expands into calls of the function binary-append.
Examples: |
| > (append nil nil) |
'() |
| > (append nil (list 1 2)) |
'(1 2) |
| > (append (list 1 2) (list 3 4)) |
'(1 2 3 4) |
| (binary-append x y) → t |
| x : (true-listp x) |
| y : t |
Concatenates two lists. Returns a new list containing all the items from
x followed by all the items from y.
Examples: |
| > (binary-append (list 1 2 3) (list 4 5 6)) |
'(1 2 3 4 5 6) |
| > (binary-append (list 1 2 3) 4) |
'(1 2 3 . 4) |
| > (binary-append 5 "<-error") |
/Users/cce/git/planet/dracula/lang/primitive-procedures/acl2 |
-prims.ss: (region Dracula Program) broke the contract |
(xargs :guard (true-listp x)) on binary-append; |
x = 5 |
y = "<-error" |
| (mv x ...) |
Form for returning multiple values. This is like list, but with the
restriction that if a function returns using mv, then it must always
return the same number of values.
Example: |
| > (mv 1 2 3 4) |
'(1 2 3 4) |
| (revappend x y) → t |
| x : (true-listp x) |
| y : t |
Examples: |
| > (revappend nil nil) |
'() |
| > (revappend nil (list 1 2)) |
'(1 2) |
| > (revappend (list 1 2) (list 3 4)) |
'(2 1 3 4) |
| > (revappend (list 1 2) 3) |
'(2 1 . 3) |
| (list elem ...) |
Creates a new true list containing all the given elements.
| (list* elem ... tail) |
| (atom-listp x) → t |
| x : t |
Reports whether x is a list of atoms.
Examples: |
| > (atom-listp (list 2 3 4)) |
't |
| > (atom-listp (list (list 23 34) 45)) |
'() |
| (character-listp x) → t |
| x : t |
Reports whether x is a list of characterp elements.
Examples: |
| > (character-listp (list #\a #\b)) |
't |
| > (character-listp (list #\a "b")) |
'() |
| (eqlable-listp x) → t |
| x : t |
Reports whether x is a list of eqlablep elements.
Examples: |
| > (eqlable-listp nil) |
't |
| > (eqlable-listp (cons 4 nil)) |
't |
| > (eqlable-listp t) |
'() |
| (integer-listp x) → t |
| x : t |
Reports whether x is a list of integerp elements.
Examples: |
| > (integer-listp nil) |
't |
| > (integer-listp (list 24 -21 95)) |
't |
| > (integer-listp (list 53 44 "number")) |
'() |
| (keyword-value-listp x) → t |
| x : t |
Reports whether x is of even length and every other element in the list satisfies keywordp.
Examples: |
| > (keyword-value-listp (list :a 1 :b 2 :c 3)) |
't |
| > (keyword-value-listp (list 'a 1 'b 'c 3)) |
'() |
| (proper-consp x) → t |
| x : t |
Reports whether x is a proper (nil-terminated) nonempty list
Examples: |
| > (proper-consp nil) |
'() |
| > (proper-consp (list 1 2 3)) |
't |
| > (proper-consp (cons 1 2)) |
'() |
| (rational-listp x) → t |
| x : t |
Reports whether x is a list of rationalp elements.
Examples: |
| > (rational-listp (list 1 2/5 3)) |
't |
| > (rational-listp (list 1 2/5 "number")) |
'() |
| (standard-char-listp x) → t |
| x : t |
Reports whether x is a list of standard-char-p elements.
Examples: |
| > (standard-char-listp (list #\a #\b #\c)) |
't |
| > (standard-char-listp (list 1 2 3)) |
'() |
| (string-listp x) → t |
| x : t |
Reports whether x is a list of stringp elements.
Examples: |
| > (string-listp (list "ab" "cd" "ef")) |
't |
| > (string-listp (list 1 2 3)) |
'() |
| (symbol-listp x) → t |
| x : t |
Reports whether x is a list of symbolp elements.
Examples: |
| > (symbol-listp (list 'ab 'cd 'ef)) |
't |
| > (symbol-listp (list 1 2 3)) |
'() |
| (true-list-listp x) → t |
| x : t |
Reports whether x is a list of true-listp elements.
Examples: |
| > (true-list-listp (list 1 2 3 4 5)) |
'() |
| > (true-list-listp '((1) (2) (3) (4) (5))) |
't |
| (true-listp x) → t |
| x : t |
Reports whether x is a proper nil-terminated list.
Examples: |
| > (true-listp (list 1 2 3 4 5)) |
't |
| > (true-listp "list") |
'() |
Examples: |
| > (butlast (list 1 2 3) 1) |
'(1 2) |
| > (butlast (list 1 2 3) 2) |
'(1) |
| > (butlast (list 1 2 3) 3) |
'() |
| (fix-true-list x) → t |
| x : t |
Examples: |
| > (fix-true-list (list 1 2 3)) |
'(1 2 3) |
| > (fix-true-list (cons 1 (cons 2 3))) |
'(1 2) |
| > (fix-true-list "abc") |
'() |
| > (fix-true-list 5) |
'() |
Finds the length of the given list. Returns 0 if lst is not a list.
| (make-list n) → true-listp |
| n : (and (integerp n) (<= 0 n)) |
Makes a list of the given length, filling it in with nil.
Gets the nth element of lst
Gets the nth cdr of the given list
| (reverse x) → t |
| x : (or (true-listp x) (stringp x)) |
Reverse the given list or string
| (update-nth n v lst) → t |
| n : (and (integerp n) (<= 0 n)) |
| v : t |
| lst : (true-listp l) |
Replaces the nth (0-based) position in lst with the value v. If n is greater than the length of lst, then update-nth will add padding to the end of the list consisting of nil values.
Examples: |
| > (update-nth 0 'z '(a b c d e)) |
'(z b c d e) |
| > (update-nth 8 'z '(a b c d e)) |
'(a b c d e () () () z) |
| (first lst) |
first member of the list
| (second lst) |
| (third lst) |
| (fourth lst) |
fourth member of the list
| (fifth lst) |
fifth member of the list
| (sixth lst) |
Sixth member of the list
| (seventh lst) |
| (eighth lst) |
eighth member of the list
| (ninth x) |
| (tenth lst) |
| (last lst) |
last member of the list
| (rest lst) |
The same as cdr