Where is the state? What changes in response to the send? Here, it'd be the cheese, so it'd make sense to have the cheese be the receiver; but a real answer com

Where is the state? What changes in response to the send? Here, it'd be the cheese, so it'd make sense to have the cheese be the receiver; but a real answer comes from moving further toward the Actor perspective. Given a distributed system with message passing, how do you choose to allocate locations to items of mutable state? That choice gives you your answer. All single-receiver systems have a problem when faced with multiple otherwise-independent pieces of state that have to change in response to a given combination. You end up encoding various kinds of transaction to keep every member of the group on the same page. Multiple-dispatch systems don't have that problem, but the tradeoff is that they're no longer message passing: all the "recipients" of a "message" live logically in the "same" location for the purposes of handling a given invocation, and if they're actually physically separated, the language implementer has to do the job of providing the illusion (e.g. via transactions) that they're in the same place.