What are the rules concerning implicit treatment of barewords as strings when Perl knows it's a hash key? If I didn't know better, I would have thought that the same rules as an identifier apply. But I've seen a leading - character used, such as in named parameters to functions. For example: 
require v5.8;
use strict;
use warnings;

my %XX;

$XX{a}= 1;
$XX{-b}= 2;
$XX{+c}= 3;  #bareword 'c' not allowed.  Interpreted as + applied to f
+unction call c().

print (join (", ", keys (%XX)), "\n");

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The -b is taken implicitly as '-b', but the same doesn't happen with +c.

Is anything allowed before, among, after the letters besides this? I can't find anything in the perldocs.

—John

In reply to bareword hash keys by John M. Dlugosz

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