var pipe=Thread.Pipe(); // used to connect the two threads
fcn{ while(1){ pipe.write((0.0).random(1.0)) } }.launch();  // generator
fcn{    // consumer/calculator
   N:=0; M:=SD:=sum:=ssum:=0.0;
   while(1){
      x:=pipe.read(); N+=1; sum+=x; ssum+=x*x;
      M=sum/N; SD=(ssum/N - M*M).sqrt();
      if(0==N%100000)
	 println("N:%,10d  mean:%.5f std dev:%.5f".fmt(N,M,SD));
   }
}.launch();

Atomic.sleep(60*60);  // wait because exiting the VM kills the threads