Not that it solves your immediate problem (well, not in a practical timeframe anyway), but Perl 6 will have a much easier way to handle this kind of comparison:

    $x =~ $y
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From the latest Exegesis (which is now finished and coming RSN to a perl.com near you):

The humble Perl 5 "match a string against a regex" operator is promoted in Perl 6 to a "smart-match an anything against an anything" operator. So now:

    if ($val1 =~ $val2) {...}
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works out the most appropriate way to compare its two scalar operands and does so. The result might be a numeric comparison ($val1 == $val2) or a string comparison ($val1 eq $val2) or a subroutine call ($val1.($val2)) or a pattern match ($val1 =~ /$val2/) or whatever else makes the most sense for the actual run-time types of the two operands.

This new turbo-charged "smart match" operator will also work on arrays and hashes and lists:

    if @array =~ $elem {...}        # true if @array contains $elem

    if $key =~ %hash {...}          # true if %hash{$key}

    if $value =~ (1..10) {...}      # true if $value is in the list

    if $value =~ ('a',/\s/,7) {...} # true if $value is eq to 'a'
                                    #   or if $value contains whitespa
+ce
                                    #   or if $value is == to 7
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That final example illustrates some of the extra intelligence that Perl 6's =~ has: when one of its arguments is a list (not an array), the "smart match" operator recursively "smart matches" each element and ORs the results together, short-circuiting if possible.

Larry hasn't said so explicitly, but I'm pretty sure that two undefs will also compare equal (silently) under the new =~.