$regex = '(\w+)|(\d+)|(\s+)|([^\w\d\s]+)';
$text = 'The world is foo 2!';

while ( $text=~s/^$regex// ) {
    print '\w+',$/ if $1;
    print '\d+',$/ if $2;
    print '\s+',$/ if $3;
    print '[^\w\d\s]+',$/ if $4;
}
[download]

$regex = '(\w+)|(\d+)|(\s+)|([^\w\d\s]+)';
$text = 'The world is foo 2!';

while ( $text=~s/^$regex// ) {
    print '\w+',$/ if defined $1;
    print '\d+',$/ if defined $2;
    print '\s+',$/ if defined $3;
    print '[^\w\d\s]+',$/ if defined $4;
}
[download]

Also the $1 was not printing as there were no capturing parens in your regular expression.

update: striked out old code, and updated it as per Abigail-II's suggestion below.

-enlil