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
53
54
55
56
57
58
59
|
/* -*- mode::rust;indent-tabs-mode::nil -*-
* Implementation of 99 Bottles of Beer
* http://99-bottles-of-beer.net/
*/
use std;
import int;
import str;
tag bottle { none; dual; single; multiple(int); }
fn show(b: bottle) {
alt b {
none. {
log "No more bottles of beer on the wall, " +
"no more bottles of beer,";
log "Go to the store and buy some more, " +
"99 bottles of beer on the wall.";
}
single. {
log "1 bottle of beer on the wall, 1 bottle of beer,";
log "Take one down and pass it around, " +
"no more bottles of beer on the wall.";
}
dual. {
log "2 bottles of beer on the wall, 2 bottles of beer,";
log "Take one down and pass it around, " +
"1 bottle of beer on the wall.";
}
multiple(n) {
let nb: str = int::to_str(n, 10u);
let mb: str = int::to_str(n - 1, 10u);
log nb + " bottles of beer on the wall, " + nb + " bottles of beer,";
log "Take one down and pass it around, " + mb +
" bottles of beer on the wall.";
}
}
}
fn next(b: bottle) -> bottle {
alt b {
none. { ret none; }
single. { ret none; }
dual. { ret single; }
multiple(3) { ret dual; }
multiple(n) { ret multiple(n - 1); }
}
}
// Won't need this when tags can be compared with ==
fn more(b: bottle) -> bool { alt b { none. { ret false; } _ { ret true; } } }
fn main() {
let b: bottle = multiple(99);
let running: bool = true;
while running { show(b); log ""; running = more(b); b = next(b); }
}
|
