#!/usr/bin/perl -w
use strict;
use warnings;

# Build a continuation to return the series of interest
sub make_a_continuation {
    # Variables the continuation uses
    my $max = shift;
    my $first = 1;

    # Return an anonymous function ref to generate next item
    return sub {
        $first++ * 100 + 300 + 200;
    }
}

# Build a couple continuations
my $get_next = make_a_continuation(50);
my $get_another = make_a_continuation(100);
# None of the data elements in the two series exists yet!  You'll
# have to create them as you need them by calling the appropriate
# continuation, e.g. &$get_next.

for my $loop (1..100) {
    # Randomly create & print items from the series
    print &$get_next . "\n" if rand(5) < 2.0;
    print &$get_another . "\n" if rand(5) < 3.5;
}

##</code><code>##

$ ./continuation.pl
Next: 600
Another: 600
Another: 700
Next: 700
Next: 800
Another: 800
Next: 900
Another: 900
Another: 1000
Another: 1100
Next: 1000