I'm not sure about this anymore, it's already legal syntax and could conflict with older code.

  DB<33> $h{!A}=1

  DB<34> $h{!(A)}=1

  DB<35> $h{!("A")}=1

  DB<36> x \%h
0  HASH(0x32dad38)
   '' => 1
  DB<37>
[download]

One could consider something like @h!{LIST}

  DB<40> @h!{"A"} = (1)
syntax error at ...
[download]

But still, is adding another obscure operation to Perl worth it?

> One purpose of this post was to nudge Perl language developers to consider exclude-slices, with maximum elegance and minimum overhead (Logging like this happens every few lines of code for me).

I think we need a meta discuss, what "good" syntax is.

"Elegance" alone doesn't help if the use case is so obscure that you never use it.

For instance I saw delete local SLICE before, but didn't remember or ever used it till now.

I'm a fan of orthogonality, the combination of syntax should be productive and easily predictive instead of being limited to isolated edge-cases.

This special case interferes somehow with Perl's lacking abilities for set-operations.

Probably a combined approach would be a better return of investment.

edit

Furthermore:

IMHO A named "speaking" operator like ->excl would be a better choice than investing into a short symbol like '!'.

Don't forget that various parsers like perl-tidy need to be updated if ! was introduced.