sub make_iter {
    my @values = @_;
    my $idx = -1;
    
    return sub {
         # check if we are out of values, 
         # return a value or undef if we're out
         return (++$idx > $#values) ? undef : $values[$idx];
    }
}

my $iter = make_iter(3,4,6,7);
print while( $_ = $iter->() );