actors style of concurrent programming

from <<Programming in scala>>

• Actors should not block
• Communicate with actors only via messages
• Prefer immutable messages
• Make messages self-contained

引用

A balanced attitude for Scala programmers

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.