#! perl -slw
use strict;

sub recurse {
    print \$_[0];
    print ">> '$_[ 0 ]'";
    if( length $_[ 0 ] ) {
        recurse( substr( $_[ 0 ] , 1, -1 ) );
        $_[0] = " ( $_[0] ) ";
    }
    print "<< '$_[0]'";
    return;
}

my $str = 'abcdefghij';
recurse $str;

print $str;

__END__
SCALAR(0x8126a70)
>> 'abcdefghij'
LVALUE(0x8126bc0)
>> 'bcdefghi'
SCALAR(0x812a454)
>> 'cdefgh'
SCALAR(0x812a520)
>> 'defg'
SCALAR(0x812a5ec)
>> 'ef'
SCALAR(0x812a6b8)
>> ''
<< ''
<< ' ('
<< ' ( d'
<< ' ( c ('
<< ' ( b ( c'
<< ' ( a ( b ( c (  ) d  ) (  ) ef ) ghij ) '
 ( a ( b ( c (  ) d  ) (  ) ef ) ghij )