Actalk [1] provided actor-like asynchronous communication on top of Smalltalk.
[1] Briot, Jean-Pierre. “Actalk: A Testbed for Classifying and Designing Actor Languages in the Smalltalk-80 Environment.” ECOOP (1989).
[1] Briot, Jean-Pierre. “Actalk: A Testbed for Classifying and Designing Actor Languages in the Smalltalk-80 Environment.” ECOOP (1989).
See the following: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3418003