You can't do that without an explicit loop. It's the nature of hash assignments. The right-hand list is only evaluated once, with competing keys successively overwriting each other on assignment, so it's not possible to do such a calculation.

As an aside, Perl6 hyperops would allow this. The closest Perl5 gets is

++$_ for @count{ @a };

[download]

Makeshifts last the longest.

In reply to Re: How can I populate a hash? by Aristotle
in thread How can I populate a hash? by Anonymous Monk

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