Max (7) [Avatar] Offline
Question to Roland, the author. Thanks for the book, it is very solid and pleasant to read.

Currently digesting Chapter 3 that provides an overview of concurrency abstractions.

Could you kindly comment/clarify the topic of composability of Actors (like functional composition)?

Is it possible?
What are advances (if any) in this area?
Is it relevant at all for Actor model?
What are difficulties or problems?
Any references, links?
Roland Kuhn (17) [Avatar] Offline
This is a question I am also deeply interested in, and it has not yet been fully answered. Actors are composed to form systems, but their composition does not work like for functions: functions are entirely passive entities who have no control over their own evaluation, whereas actors are active. Therefore actors collaborate where functions would otherwise be composed mathematically. Gul Agha’s thesis is an excellent read on this topic, cf.

When it comes to compositional properties and their static compile-time expression, I have written two blog articles ( and am currently working on Akka Typed Sessions. You may also find recent articles on the Akka team blog interesting.
Max (7) [Avatar] Offline
I'll dig there, never heard of Session Types. Thanks a lot.