{
   my %state;
   sub recursive {
       my $arg = shift;
       ...
       if( ( $arg = $state{ $arg } ) == ... ) {
            return recursive( $arg );
       else {
            return 0
       }
   }
}


##</code><code>##

sub rec_helper {
    my %state;
    my $recursive;
    $recursive = sub {
        my( $arg ) = shift;
        ...
        if( ( $arg = $state{ $arg ) ) == ... ) {
             return $recursive->( $arg );
        }
        else {
             return 0;
        }
    };
}


##</code><code>##

sub recursive {
    my( $state, $arg ) = @_;
    ...
    if( ( $arg = $state->{ $arg } ) == ... ) {
         return recursive( $state, $arg );
    }
    else {
         return 0;
    }
}

sub rec_helper{
    my $arg = shift;
    my %state;
    return recursive( \%state, $arg );
}