http://sulzmann.blogspot.com/2008/10/actors-with-multi-headed-receive.html

Here's a simple example of a market-place actor

receive
  Seller x, Buyer x -> "match found"

We employ the combination of multiple messages in a receive pattern and non-linear patterns to test for a matching seller and a buyer. Non-linear patterns are in fact a short-hand for guards. That is, the above is equivalent to

receive
  Seller x, Buyer y when x == y -> "match found"

Получается своего рода ассоциативная память, позволяющая делать весьма разветвлённые dataflow сети.