use warnings;
use strict;

sub Iterator (&) { return $_[0] }  # syntactic sugar per hop

sub cyclic_array_iter {

    my @array = @_;  # copy of array to iterate
    my $i     = $[;  # iterated array index

    return Iterator { return } unless @array;  # maybe die here?

    return Iterator {

        if (@_) {
            $i = $_[0];
            $i = $[ if $i > $#array or $i < $[;
            return;
            }

        my $element = $array[$i++];
        $i = $[ if $i > $#array;

        return $element;

        };

    }


use Test::More 'no_plan';

sub play { return "$_[0] likes to play"; }
sub eat  { return "$_[0] likes to eat";  }
sub nap  { return "$_[0] likes to nap";  }

my @people     = qw(tom harry diana nick sally henry);
my @activities = (\&play, \&eat, \&nap);

my $person   = cyclic_array_iter(@people);
my $activity = cyclic_array_iter(@activities);

for my $name (@people) {
    is($person->(), $name, "person: $name");
    }

is($person->(), 'tom',   'wrap: person: tom');
is($person->(), 'harry', 'person: harry');
$person->(0);
is($person->(), 'tom',   'after re-indexing: person: tom');
is($person->(), 'harry', 'person: harry');
$person->(-1);
is($person->(), 'tom',   'after bad index (-1): person: tom');
is($person->(), 'harry', 'person: harry');
$person->(1 + $#people);
is($person->(), 'tom',   'after bad index (1 beyond): person: tom');
is($person->(), 'harry', 'person: harry');
$person->(99_999);
is($person->(), 'tom',   'after bad index (big): person: tom');

is($activity->()->($person->()), 'harry likes to play', 'harry,play');
$activity->()->($person->());
is($activity->()->($person->()), 'nick likes to nap',   'nick,nap');
is($activity->()->($person->()), 'sally likes to play', 'sally,play');
is($activity->()->($person->()), 'henry likes to eat',  'henry,eat');
is($activity->()->($person->()), 'tom likes to nap',    'tom,nap');

##</code><code>##

>perl cyclic_array_iter_1.pl
ok 1 - person: tom
ok 2 - person: harry
ok 3 - person: diana
ok 4 - person: nick
ok 5 - person: sally
ok 6 - person: henry
ok 7 - wrap: person: tom
ok 8 - person: harry
ok 9 - after re-indexing: person: tom
ok 10 - person: harry
ok 11 - after bad index (-1): person: tom
ok 12 - person: harry
ok 13 - after bad index (1 beyond): person: tom
ok 14 - person: harry
ok 15 - after bad index (big): person: tom
ok 16 - harry,play
ok 17 - nick,nap
ok 18 - sally,play
ok 19 - henry,eat
ok 20 - tom,nap
1..20