LISP Reference Material

List Operations

CAR CDR CAAR CADR CDAR CDDR CAAAR CAADR CADAR CADDR CDAAR CDADR CDDAR CDDDR
; Plus 16 more (all combinations of four A's and D's).

CONS and .  ; Both create a cons cell.

LIST        ; Creates as many cons cells as needed.
            ; CDR of last one will be NIL.

(NTHCDR n list)
(ELT list index)
(ELT string index)

(LAST list)
(LENGTH list)
(LENGTH string)
(REVERSE list)
(REVERSE string)
(APPEND list list ...)

Predicates
; Return NIL for false, T for true.

LISTP
NUMBERP
ATOM
(MEMBER element list)

Get true/false value from user
(y-or-n-p “string)     ; Anything starting with y or n is valid.
(yes-or-no-p string)  ; Must answer "yes" or "no" exactly.

Equality
EQ EQL EQUAL EQUALP

Arithmetic / Logic
(= n ...), (+ n ...), etc.

AND OR                ; Short-circuit evaluation.
                      ; Can be used for testing.
NOT

Testing
(IF test true-expression false-expression)

(COND   (test consequent ...)   ; Returns result of last consequent
        ...
        (T    consequent ...))  ; Conventional last test.

Loops
(DOLIST (index list [result]) body)
(DOTIMES(index count [result]) body)  ; index starts at zero.
(DO (index [initial-value [repetitions]]…) (test result) body)

Output

(PRINT string)
(PRINT symbol)
(PRINT list)

(FORMAT do-print? format-string value ...)

; If do-print? is not NIL, print the result and return NIL.
; Otherwise return the formatted string without printing it.

  ~a  ; Print value of a symbol.
  ~%  ; Print a newline.

Variables and Scope

(SETF symbol value)       ; Change the value of a symbol.

(DEFVAR var value)        ; Global variable, can't be redefined.
(DEFPARAMETER var value)  ; Global variable, can be redefined.
(DEFCONSTANT var value)   ; Global variable, error to try to change.

(DEFUN (parameter ...) body)  ; Function definition.

(DECLARE (SPECIAL var ...))   ; Dynamic scope.

(LET ((var value)...) body)   ; Local variables.
                              ; Can be done just before the body 
                              ; in either LET or DEFUN.