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

sub foo { print "FOO!\n" }
sub bar { print "BAR!\n" }

sub menu { ... }

my ($mainmenu, $submenu);

$submenu = [
    'Submenu',
    'Bar',                  => \&bar,
    'Back to previous menu' => undef,
];

$mainmenu = [
    'Main menu',
    'Foo'        => \&foo,
    'Submenu...' => $submenu,
    'Exit'       => undef,
];

menu($mainmenu);