I changed it to also print out the values, and am delighted to find: 
# on cygwin

perl -e 'print "$_ => $::{$_}\n" for keys %::'

__OUTPUT__

/ => *main::/
stderr => *main::stderr
_<.\win32.c => *main::_<.\win32.c
_<perllib.c => *main::_<perllib.c
utf8:: => *main::utf8::
" => *main::"
CORE:: => *main::CORE::
DynaLoader:: => *main::DynaLoader::
stdout => *main::stdout
attributes:: => *main::attributes::
&#8597; => *main::&#8597;
stdin => *main::stdin
ARGV => *main::ARGV
INC => *main::INC
ENV => *main::ENV
Regexp:: => *main::Regexp::
_<..\perlio.c => *main::_<..\perlio.c
UNIVERSAL:: => *main::UNIVERSAL::
$ => *main::$
main:: => *main::main::
- => *main::-
Win32:: => *main::Win32::
PerlIO:: => *main::PerlIO::
_<..\universal.c => *main::_<..\universal.c
0 => *main::0
 => *main::
@ => *main::@
_<..\xsutils.c => *main::_<..\xsutils.c
STDOUT => *main::STDOUT
IO:: => *main::IO::
&#8593; => *main::&#8593;
_ => *main::_
+ => *main::+
STDERR => *main::STDERR
Internals:: => *main::Internals::
STDIN => *main::STDIN
DB:: => *main::DB::
<none>:: => *main::<none>::

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This "confirms" what I read somewhere that the symbol table contains the typeglob of the key, which apparently works for any package. Is there anyway to find out what the typeglobs really are? (i.e, its scalar value, array value, etc.)

In reply to Re: keys %:: by johnnywang
in thread keys %:: by blazar

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