There is no output. ActiveState 5.6.1 build 633.

[Added split /\W+/ splits the entire string which ends just before the print() at the end. Each element of the result from split() is a fragment of text that appears to be perl code but really isn't. The y...c fragment adds the string length to the $, length which is used as the offset parameter to the vec function.

Each part of the input is an incremental offset to a bitstring being built up by vec in $\. The actual bits are being set by using vec as an lvalue via the ++ operator.

The lone print at the bottom outputs nothing followed by the output record separator $\ which just happens to include the desired text.

Bravo! That was a very clever expression.]