data Msg
  = Ok String
  | Ad String

data ChatF a
  = Write Msg a
  | Read (Msg → a)
  | Kick a

derive instance functorChatF ∷ Functor ChatF

type CHAT = FProxy ChatF

_chat = SProxy ∷ SProxy "chat"

write :: ∀ r. Msg → Run (chat :: CHAT | r) Unit
write msg = Run.lift _chat $ Write msg unit

read :: ∀ r. Run (chat :: CHAT | r) Msg
read = Run.lift _chat $ Read identity

kick :: ∀ r. Run (chat :: CHAT | r) Unit
kick = Run.lift _chat $ Kick unit

scenario :: ∀ r. Run (chat :: CHAT | r) Unit
scenario = do
  reply ← read
  case reply of
    Ok s → write $ Ok "привет"
    _    → kick