Frequently Used LISP Commands
car (car L) returns the value of the first element of L, which may be an atom or a list.
cdr (cdr L) returns the list that remains when the first element has been removed. The value is a list (which may be the empty list)
cons (cons x L) creates a new list consisting of the list L with an extra element inserted at the front. For instance, (cons 3 '(1 2)) returns (3 1 2).
null? (null? L) a predicate, returns T if L is the null list, NULL otherwise.
list? (list? L) a predicate, returns T if L is a list, NULL otherwise.
+

(+ a b)
(+ a b .... n)

 arithmetic operation, returns sum of its arguments. May have any number of arguments.
-
*
/		 (- a b)
(* a b)
(/ a b)		 arithmetic operations, return a-b, a*b, a/b, respectively.
first (first L) returns the first element of list L. Same as (car L).

cadr
cddr
caddr
...

(cadr L)
(cddr L)
(caddr L)

 shorthand for (car (cdr L)), (cdr (cdr L)), (car (cdr (cdr L))), ...
define (define x expr) create a variable x with the value of expr assigned as value. Examples: (define x 3), (define y (cdr L)). Note expr is evaluated then assigned.
lambda (lambda (args) expr)

create a function with args (a list of 0 or more atoms) as arguments, and return value specified by expr. Arguments are passed by value. Example:
(define last_element
(lambda (L)
(cond
((null? L) NULL)
((null? (cdr L)) (car L))
(T (last_element (cdr L))
))
)

     

To load a file of LISP commands:

(define filepath "C:\\Program Files\\MIT\\scheme\\myProg.txt")

(load filepath)