gistfile1.p6

/usr/bin/env perl6

use v6.c;

my $line-source = Proc::Async.new("perl6", "bin/line-source.p6", :w);

react {
    whenever $line-source.stdout -> $l is copy {
        $line-source.put: $l++;
        if (1..1000).pick > 999 {
            say $l.chop;
            # sleep 2; # do not sleep here as it will block everything else
        }
    }
    whenever $line-source.start { done } # done will bail out from react
    whenever signal(SIGINT) { $line-source.kill } # once the process is finished it will go to “whenever $line-source.start”
    whenever Promise.in(2) { $line-source.put: 1 }
}