runa/runa-std/actors/counter.rn

pub fn handle(ctx, state, sender, message) {
    if message.op == "start" {
        ctx.send(ctx.this, #{op: "add", value: 1});
        state + 1
    } else if message.op == "add" {
        state + message.value
    } else {
        panic("unknown counter operation")
    }
}