$foo->[0] is dereferencing an arrayref
$foo->{bar} is dereferencing a hashref
$foo->(@blah) is dereferencing (and invoking) a function-ref
$foo->bar is calling the method "bar" that is defined in the class that $foo has been [bless]'ed into.

##</code><code>##

my $text_index;
if ($token->[0] eq 'T') {
    $text_index = 1;
} else {
    $text_index = -1;
}