1
0
mirror of https://github.com/vlang/v.git synced 2023-08-10 21:13:21 +03:00
v/examples/lander.v

63 lines
819 B
V
Raw Normal View History

2020-07-06 19:09:38 +03:00
// Example of sum types
// Models a landing craft leaving orbit and landing on a world
import rand
import time
struct Moon {
}
struct Mars {
}
2020-07-06 19:09:38 +03:00
fn (m Mars) dust_storm() bool {
return rand.int() >= 0
}
struct Venus {
}
type World = Mars | Moon | Venus
2020-07-06 19:09:38 +03:00
struct Lander {
}
2020-07-06 19:09:38 +03:00
fn (l Lander) deorbit() {
println('leaving orbit')
}
2020-07-06 19:09:38 +03:00
fn (l Lander) open_parachutes(n int) {
println('opening $n parachutes')
}
fn wait() {
println('waiting...')
2021-02-27 20:41:06 +03:00
time.sleep(1 * time.second)
2020-07-06 19:09:38 +03:00
}
fn (l Lander) land(w World) {
if w is Mars {
for w.dust_storm() {
2020-07-06 19:09:38 +03:00
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{}
2020-07-06 19:09:38 +03:00
l.land(Venus{})
l.land(Mars{})
}