blob: ad2600d5c4169d154260ba79db2a7ec64a3a2917 (
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
53
54
55
56
57
58
59
60
61
62
|
// Example of sum types
// Models a landing craft leaving orbit and landing on a world
import rand
import time
struct Moon {
}
struct Mars {
}
fn (m Mars) dust_storm() bool {
return rand.int() >= 0
}
struct Venus {
}
type World = Mars | Moon | Venus
struct Lander {
}
fn (l Lander) deorbit() {
println('leaving orbit')
}
fn (l Lander) open_parachutes(n int) {
println('opening $n parachutes')
}
fn wait() {
println('waiting...')
time.sleep(1 * time.second)
}
fn (l Lander) land(w World) {
if w is Mars {
for w.dust_storm() {
wait()
}
}
l.deorbit()
match w {
Moon {} // no atmosphere
Mars {
// light atmosphere
l.open_parachutes(3)
}
Venus {
// heavy atmosphere
l.open_parachutes(1)
}
}
println('landed')
}
fn main() {
l := Lander{}
l.land(Venus{})
l.land(Mars{})
}
|
