// See http://www.tbray.org/ongoing/When/200x/2009/10/26/Messaging

$module ParCounter;

$use Arithm Box Parallel StdIO System;

$public $func NewCounter = t.counter;
$public $func Incr t.counter = ;
$public $func Count t.counter = s.n;

NewCounter =
	(<MsgBox> <Box 0>) :: t.counter,
	<ParApply &DoCounting t.counter>,
	t.counter;

$func DoCounting t.counter = ;
DoCounting (s.msgbox s.box) =
	$iter {
		<Recv s.msgbox> : e,
			<Box.Get s.box> : s.n,
			<Box.Store s.box <Add s.n 1>>;
	}, $fail;

Incr (s.msgbox s.box) = <Send s.msgbox 1>;

Count (s.msgbox s.box) =
	<Box.Get s.box> : s.n,
	s.n;

$func Main = e;
Main =
	<NewCounter> :: t1,
	<NewCounter> :: t2,
	<NewCounter> :: t3,
	<Incr t1>,
	<Incr t2>,
	<Incr t2>,
	<Incr t2>,
	<Incr t1>,
	<WriteLn <Count t1> <Count t2> <Count t3>>,
	<Exit 0>;