use Algorithm::Loops qw( NestedLoops );

my @hashes = ( \%hash0, \%hash1, \%hash2, \%hash3 );

my @key_lists = map [ keys %$_ ], @hashes;

NestedLoops(\@key_lists, sub {
   my @keys = @_;
   say join ', ' map "$keys[$_] => $hashes[$_]{$keys[$_}}", 0..$#keys;
});

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In reply to Re: Dynamically create a foreach loop within a foreach loop? by ikegami
in thread Dynamically create a foreach loop within a foreach loop? by jdlev

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