0. #lang racket
1.  
2. ;; fixed by following advice from #racket
3.  
4. (require math/array)
5.  
6. (define (world dimensions)
7.   (array->mutable-array
8.    (make-array dimensions 7)))
9.  
10. (define (tiles elevation)
11.   (cond
12.     [(< elevation 8)
13.      #\~]
14.     [(< elevation 10)
15.      #\:]
16.     [(< elevation 12)
17.      #\space]
18.     [(< elevation 14)
19.      #\n]
20.     [else
21.      #\A]))
22.  
23. (define (view-world map south east height width)
24.   (define (view-row south east width)
25.     (if (= width 1)
26.         (list (tiles (array-ref map (vector south east))))
27.         (append
28.          (list (tiles (array-ref map (vector south east))))
29.          (view-row south (+ east 1) (- width 1)))))
30.   (if (= height 1)
31.       (list->string (view-row south east width))
32.       (string-append
33.        (list->string (view-row south east width))
34.        "\n"
35.        (view-world map (+ south 1) east (- height 1) width))))
36.  
37. (define the-world (world (vector 8 8)))
38.  
39. (define out
40.   (open-output-file "myData" #:exists 'truncate))
41. (write (array->list* the-world) out)
42. (close-output-port out)
43.  
44. (define in
45.   (open-input-file "myData"))
46. (display (view-world (list*->array (read in) number?) 1 1 5 5))
47. (close-input-port in)

=>

open-output-file: `write' access denied for myData

out: undefined;

cannot reference an identifier before its definition

in module: 'm

out: undefined;

cannot reference an identifier before its definition

in module: 'm

open-input-file: cannot open input file

path: /home/pasterack/racket68/share/pkgs/web-server-lib/w

eb-server/default-web-root/htdocs/myData

system error: No such file or directory; errno=2

in: undefined;

cannot reference an identifier before its definition

in module: 'm

in: undefined;

cannot reference an identifier before its definition

in module: 'm