keyword
event
event Name { field: T = default }
event declares a public event — a named signal carrying a flat payload of typed fields (each with a default; the payload may be empty). Where lifecycle hooks are the closed reactions the author compiles in, events are the open runtime surface a game exposes to mods: an in-language listener registers with @On(Name) and reads the payload fields by name, and emit Name(field: value, …) fires every listener in declaration order as a direct call. It all desugars to a generated function — there is no interpreter and no dispatch table — and a program that declares no event compiles byte-for-byte as before. Mark an event cancellable when a listener should be able to veto the action it announces.
Example
program EventExample {
event EnemyDefeated { points: int = 0 }
var score: int = 0
@On(EnemyDefeated) handler AddScore { score = score + points }
@On(EnemyDefeated) handler PlayChime { Screen.status("enemy down") }
handler ScoreOnKey phase Update {
if Input.key() == 'k' { emit EnemyDefeated(points: 10) }
}
handler DrawWorld phase Render {
Screen.clear(Color.MidnightBlue)
Screen.draw_number(x: 4, y: 4, value: score, color: Color.Gold, scale: 1)
Screen.show()
}
}