Mixing Metaphors: Actors as Channels and Channels as Actors

Channel- and actor-based programming languages are both used in practice, but the two are often confused. Languages such as Go provide anonymous processes which communicate using buffers or rendezvous points—known as channels—while languages such as Erlang provide addressable processes—known as actors—each with a single incoming message queue. The lack of a common representation makes it difficult to reason about translations that exist in the folklore. We define a calculus λch for typed asynchronous channels, and a calculus λact for typed actors. We define translations from λact into λch and λch into λact and prove that both are type- and semantics preserving. We show that our approach accounts for synchronisation and selective receive in actor systems and discuss future extensions to support guarded choice and behavioural types.