actors style of concurrent programming

from <<Programming in scala>>

[list]
[*] Actors should not block
[*] Communicate with actors only via messages
[*] Prefer immutable messages
[*] Make messages self-contained
[/list]

[quote]
[b]A balanced attitude for Scala programmers[/b]

Prefer vals, immutable objects, and methods without side effects.
Reach for them first. Use vars, mutable objects, and methods with side
effects when you have a specific need and justification for them.
[/quote]