The main reason it was implemented is because people have wanted this for at least a decade. And wanted it badly. There have been some very heated arguments about this operator (and its name, anyone remember the ||| and ?? suggestions?) in the past.

If the idea behind the feature that ~~ represents existed this long, it would have too. It is new, though. However, it gives us given/when and THAT has also been wanted for a very long time. Just see Google Groups and our own Perl Monks for proof. In fact, I think a switch statement has been asked for/about much more often than defined-or.

I read your "see no reason why it couldn't be implemented in current Perl" as being such a suggestion.

I was evaluating the technical possibility, not implying that it SHOULD be done.

Well, you saw no reason why it couldn't be implemented in current Perl - but I did. And that's the reason.

It could, but it probably won't.

Or, well, I asked xmath if it would be easy to implement ~~ so that it called a perl side sub. This would enable me to do the comparisons themselves in Perl, probably reusing some logic from Switch.pm. (Consider File::Glob.) xmath answered my question by saying it wouldn't be a great deal of work, and my gut says he's already started working on it even though I haven't asked for the actual implementation yet :)

And he brought up an improbable but existing clash: foo~~bar is now foo(~~bar). But I think we should just strongly state that scalar should be written as scalar instead of ~~ ;) (Those who really want to use ~~ for the first argument of a function, can use + or parens to disambiguate.)