;; Some simple examples of programming in Scheme. Type these in one at
;; a time. If using DrScheme set the Language mode to the "Pretty Big" mode
;; under the Professional Languages tab.


; simple variable definitions and usage
(define x 1)
x
(+ x 1)

(define x '(this is a list))
x
(length x)

#t
#f

(and)
(and #t #f)
(and 0 1)

(or)
(or x)
(or #f)
(or #f #t)

(if (or 1 2) #t #f)

;; everything is a list

'() 	; the empty list
(length '())
        
(+ 1 2 3 4 5)
(* 1 2 3 4 5)
(+ 1 (* 2 3) (- 4 5))

(if (null? '()) #t #f)

'(apples oranges grapes)
(cons 'peanut '(butter and jelly))
(car '(apples oranges grapes))
(cdr '(apples oranges grapes))

;; function definition

(define (square x) (* x x))  ;; this is syntactic sugar for the next expr
(define square (lambda (x) (* x x)))

(define fact (lambda (n) 
	(if (= n 0)
	    1
	    (* n (fact (- n 1))))))