Petite Chez Scheme Version 9.5
Copyright 1984-2017 Cisco Systems, Inc.

> (+ (/ 3 5) (/ 2 7))
31/35
> six
Exception: variable six is not bound
> (define six 6)
> (+ six 2)
8
> (list 2 3 4)
(2 3 4)
> '(2 3 4)
(2 3 4)
> (list 2 six 4)
(2 6 4)
> '(2 six 4)
(2 six 4)
> (2 4 6)
Exception: attempt to apply non-procedure 2
> +
#<procedure +>
> a
Exception: variable a is not bound
> (define a (list 2 3 4))
> a
(2 3 4)
> (car 2)(define times3
  (lambda (n)
    (* n 3)))
Exception in car: 2 is not a pair
> (car a)
2
> (cdr)
Exception: incorrect argument count in call (cdr)
> (cdr a)
(3 4)
> (car (cdr a))
3
> (cadr a)
3
> (caddr a)
4
> (cadddr a)
Exception in cadddr: incorrect list structure (2 3 4)
> (caddddr a)
Exception: variable caddddr is not bound
> (define times3
  (lambda (n)
    (* n 3)))
> (define times6
  (lambda (n)
    (+ (times3 n) (times3 n))))
> (times6 7)
42
> (trace times6)
(times6)
> (trace times6 times3)
(times6 times3)
> (times6 7)
|(times6 7)
| (times3 7)
| 21
| (times3 7)
| 21
|42
42
> (trace *)
Warning in trace: redefining *; existing references will not be traced
(*)
> (define times3
  (lambda (n)
    (* n 3)))
> (times6 7)
|(times6 7)
| (* 7 3)
| 21
| (* 7 3)
| 21
|42
42
> (untrace)
(times6 *)
> (define fact
  (lambda (n)
    (if (zero? n)
	1
	(* n (fact (- n 1))))))
> (fact 5)
120
> (fact 200)
788657867364790503552363213932185062295135977687173263294742533244359449963403342920304284011984623904177212138919638830257642790242637105061926624952829931113462857270763317237396988943922445621451664240254033291864131227428294853277524242407573903240321257405579568660226031904170324062351700858796178922222789623703897374720000000000000000000000000000000000000000000000000
> (trace fact)
(fact)
> (fact 5)
|(fact 5)
| (fact 4)
| |(fact 3)
| | (fact 2)
| | |(fact 1)
| | | (fact 0)
| | | 1
| | |1
| | 2
| |6
| 24
|120
120
> (define nth-element
  (lambda (ls n)
    (cond [(null? ls) "error"]
	  [(zero? n) (car ls)]
	  [else (nth-element (cdr ls) (-n 1))])))
> (nth-element '(a b c d e f) 3)
Exception: variable \x2D;n is not bound
> (define nth-element
  (lambda (ls n)
    (cond [(null? ls) "error"]
	  [(zero? n) (car ls)]
	  [else (nth-element (cdr ls) (- n 1))])))
> (nth-element '(a b c d e f) 3)
d
>