Yes, you don't get sync for free when using the ! operator in Erlang, but that's why you use the OTP constructs like handle_call (sync) and handle_cast (async)

Yes, you don't get sync for free when using the ! operator in Erlang, but that's why you use the OTP constructs like handle_call (sync) and handle_cast (async) to model that sort of behavior... Throwing the ! operator around haphazardly can be useful, but generally it's a code smell, as things can usually be encapsulated more effectively using OTP constructs. Edit: saw you addressed this in another comment.