fiber.pl

use strict;
use warnings;
use Coro::State;
use Perl6::Say;

my $resume;
my $yield;
my $func;
{
    my $ret;
    my $main;
    my $state;

    $main = Coro::State->new;
    $state = Coro::State->new(sub {
        $func->();
    });
    
    $resume = sub {
        $main->transfer($state);
        $ret;
    };

    $yield = sub {
        $ret = shift;
        $state->transfer($main);
    };
}

$func = sub {
    my $n = 0;
    while (1) {
        $yield->($n++);
    }
};

say $resume->();
say $resume->();
say $resume->();