blob: 4c52883cafc40f9a99ae0dedbcdeb08adf1cc156 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
;;;; variables
(define my-var 15)
my-var
;; set to something else
(set! my-var 20)
;;;; functions
(define (find value lst)
(if (pair? lst)
(begin
(display (string-append "Looking at: " (number->string (car lst))
"\n"))
(if (equal? (car lst) value)
(begin (display "Found it!\n")
(car lst))
(find value (cdr lst))))
#f))
(find 5 '(1 2 3 4 5 6))
;; note that variables and functions exist in the same
;; namespace, and that we can define functions in a
;; slightly more ugly way, but looks a lot like a var
;; declaration:
(define find-x (lambda (value lst)
(if (pair? lst)
(begin
(display (string-append "Looking at: " (number->string (car lst))
"\n"))
(if (equal? (car lst) value)
(begin (display "Found it!\n")
(car lst))
(find value (cdr lst))))
#f)))
(find-x 4 '(1 2 3 4 5 6))
;;;; let
;; let as a looping construct
(let find-loop ((value 5)
(lst '(1 2 3 4 5)))
(if (pair? lst)
(begin
(display (string-append "Looking at: " (number->string (car lst))
"\n"))
(if (equal? (car lst) value)
(begin (display "Found it!\n")
(car lst))
(find-loop value (cdr lst))))
#f))
|
