kw rpc

RpcSig      = "rpc" Ident "(" [ Params ] ")" "->" Type ;

Rpc         = "rpc" Ident "(" [ IdentList ] ")" ( Block | "=>" Expr ) ;

policy Orders {
  allow get(id)        if caller.isUser(db.find(Order, id)?.userId)
  allow list, recent   if caller.has(role: .Support)
  allow *              if caller.service("billing")
  deny  delete         unless caller.has(role: .Admin) && caller is .User(mfa: true, ..)
}

@public rpc health() -> Ok
@allow(role: .Admin) rpc purge() -> Ok
@internal rpc create(…) -> Order

let prices = Broadcast<Tick>(buffer: TICK_BUFFER, slow: .DropOldest, replay: 1)

scope {
  spawn { for await t in Exchange.feed() { prices.publish(t) } }
  spawn { for await t in prices.subscribe() { ui.render(t) } }
  spawn { for await t in prices.subscribe() { stats.add(t) } }
}

impl Market {
  rpc ticks() -> stream<Shared<Tick>, Lagged> => prices.subscribe()   // for every client
}