use warnings;
use strict;

package Coroutine;
sub prototype {
    my $class = shift;
    bless shift(), $class;
}
sub instance {
    my $self = shift;
    my @sections = $self->(@_);

    return sub {
      return () unless @sections;
      (shift @sections)->(@_);
    }
}

package main;

my $coroutine = Coroutine->prototype(
    sub {
        my $foo = shift;
        my @bar = @_;
        (
          sub {
            print "1st section:\n";
            print " $_\n" for @bar;
            return $foo++;
          },
          sub {
            print "2nd section:\n";
            print " $foo\n";
            return rand() > .5 ? 'weird' : ++$foo;
          },
          sub {
            print "3rd section:\n";
            print " The end is near - goodbye cruel ";
            return pop @bar;
          }
        )
    }
);

my $wacky = $coroutine->instance(42, 'hello', 'world');
print "returned($_)\n" while ($_ = $wacky->());
print "Resetting...\n";
$wacky = $coroutine->instance('another', 'time', 'through');
print "returned($_)\n" while ($_ = $wacky->());
__END__
1st section:
 hello
 world
returned(42)
2nd section:
 43
returned(44)
3rd section:
 The end is near - goodbye cruel returned(world)
Resetting...
1st section:
 time
 through
returned(another)
2nd section:
 anothes
returned(anothet)
3rd section:
 The end is near - goodbye cruel returned(through)