;; This is a transcript from CS 314 lecture, 2/4/2004, Prof DeCarlo

Welcome to DrScheme, version 205.
Language: Standard (R5RS).
> (lambda (x) (+ x x))
#<procedure:3:2>
> ((lambda (x) (+ x x))  4)
8
> ((lambda (x) (+ x x))  (* 2 (+ 3 5)))
32
> (define double (lambda (x) (+ x x)))
#<procedure:double>
> (double 5)
10
> (double (+ 3 7))
20
> (define x (+ 3 7))
> x
10
> (double x)
20
> (define x 3)
> x
3
> (define x '((a b (b c))))
> x
((a b (b c)))

;; This is an alternative form for defining a function
;; without saying "lambda"
> (define (double x) (+ x x))
> (quote 3)
3
> (quote a)
a
> 'a
a
> a
. reference to undefined identifier: a
> x
((a b (b c)))
> +
#<primitive:+>
> double
#<procedure:double>
> quote
quote: bad syntax in: quote
> (quote 3 3)
quote: bad syntax (wrong number of parts) in: (quote 3 3)

;; Note that quote is a special form, and the arguments are
;; NOT evaluated first -- unlike +
> (quote 3)
3
> (+ 3)
3
> (quote a)
a
> (+ a)
. reference to undefined identifier: a

;; Here is a lambda with more than one argument
> (define wow (lambda (x y) (+ x y 1)))
> (wow 4 10)
15

;; You can't directly make a function that just
;; implements quote -- if you do it this way, then it
;; actually quotes the x!  (This is pretty strange, so
;; don't worry if it's confusing -- it did come up in
;; class, though)
> (define myquote (lambda (x) (quote x)))
> (quote a)
a
> a
. reference to undefined identifier: a
> (myquote a)
. reference to undefined identifier: a
> myquote
#<procedure:myquote>

;; Even though x is bound to 3, it still returns the
;; quoted symbol 'x -- in this case, the 3 is just thrown away

> (myquote 3)
x
> 3
3
> a
. reference to undefined identifier: a
> (quote x)
x
> (quote b)
b
> x
((a b (b c)))

;; here it is again, but this time using the symbol 'blah instead
;; of 'x which got a little confusing

> (lambda (x) 'x)
#<procedure:98:2>
> (lambda (x) 'blah)
#<procedure:100:2>
> ((lambda (x) 'blah) 3)
blah
> (myquote a)
. reference to undefined identifier: a
> (quote a)
a
> (define a 1)
> (myquote a)
x
> (myquote 1)
x

;; Building lists..

> (list a b c)
. reference to undefined identifier: b
> (list 'a 'b 'c)
(a b c)
> (quote (a b c))
(a b c)
> (list 3 59 1)
(3 59 1)
> (car (list 3 59 1))
3
> (cdr (list 3 59 1))
(59 1)
> (define x (list 3 59 1))
> (car x)
3
> (cdr x)
(59 1)
> (car (cdr x))
59
> (cdr (cdr x))
(1)
> (car (cdr (cdr x)))
1
> (cdr (cdr (cdr x)))
()

;; Can't apply car and cdr to an empty list

> (car ())
. car: expects argument of type <pair>; given ()
> (cdr ())
. cdr: expects argument of type <pair>; given ()
> 
(define x '(1 . 2))
> 
x
(1 . 2)
> (car x)
1
> (cdr x)
2
> (cons 1 2)
(1 . 2)
> (cons 1 (list 2))
(1 2)
> (cons 1 ())
(1)
> (cons 1)
. cons: expects 2 arguments, given 1: 1
> (cons 1 2 3)
. cons: expects 2 arguments, given 3: 1 2 3

;; Let's try to make the list (1 2 3) using only cons...

> '(1 2 3)
(1 2 3)
> (cons 1 2)
(1 . 2)
> (cons 1 (list 2 3))
(1 2 3)
> (cons 1 (cons 2 3))
(1 2 . 3)
> (cons 1 (cons 2 (cons 3 ())))
(1 2 3)
> (list 1 2 3)
(1 2 3)

;; some predicates availableon lists

> (null? (list 1))
#f
> (null? ())
#t
> (list? (list 1))
#t
> (list? '(1 . 2))
#f

> (cons 1 '(2 3))
(1 2 3)
> (cons 1 (quote (2 3)))
(1 2 3)

;; boolean operators

> (or #t #t #f)
#t
> (and #t #t #f)
#f
> (or #t)
#t
> (and #t)
#t
> (not #t)
#f
> (not #f)
#t

;; and/or can return the value of certain arguments
;; when they aren't #t's -- see the slides for a description

> (or 3 #t)
3
> (and 3 5 #t 27)
27
> (and 3 #f #t 27)
#f
> (or #f #f)
#f
> (or #f 3)
3
> (null? ())
#t
> (symbol? 'a)
#t
> (symbol? 3)
#f