CP, Message Passing | chuahou.dev

[2.3] Processes communcate using synchronous/asynchronous channels.

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[2.15] Producers should close the channel.
- [2.16] Closed channels produce Closed <: Stopped exceptions.
- [2.17] repeat { ... } = infinite loop till Stopped caught.
- [2.19] attempt {p}{q} = p but run q when Stopped caught.
- [3.10] Shared channels either closed by One side or appropriate number of either side for N2N.
[2.3, 2.15, 3.9]

trait InPort[T]  { def ?(): T;  def closeIn;  }
trait OutPort[T] { def !(x: T); def closeOut; }
trait Chan[T] extends InPort[T] with OutPort[T] { def close }
def OneOne[T], N2N[T](writers, readers), OneMany[T], ManyOne[T]
	: Chan[T]

[5.27] Buffered asynchronous channels (better performance).

def OneOneBuf[T](size): Chan[T]
def N2NBuf[T](size, writers, readers): Chan[T]

[2.26] Chan[Unit] can be used for synchronization.
- [2.29] Processes can access the same variable if synchronization ensures they never access at the same time.
[2.33] Must be wary of pass-by-reference.
[2.30] Synchronous send $s$ and receive $r$, then $s \preceq r$ and $r \preceq s$.
[4.3] alt/serve syntax used to run whichever port is ready.
- [4.7] serve is repeat { alt ( ... ) } but fair.
- [4.26] Outports.
- [4.6] AltAbort <: Stopped exception when all infeasible.
- [4.30] Cannot (a) have multiple enabled events on same port, (b) share ports, (c) use both ports of channel.

alt( in1 =?=> { x => ... }
   | (guard && in2) =?=> { x => ... }
   | out1 =!=> { expr }
   | (guard && out2) =!=> { expr } ==> { doAfter }
   )
alt(| (for (...) yield ... =?=> ...)) // | on collection