while( my $k = each %hash ) { ... }
foreach my $k ( keys %hash ) { ... }

##</code><code>##

while( my ( $k, $v ) = each %hash ) {

##</code><code>##

foreach my $k ( keys %hash ) {
    my $v = $hash{ $k };

##</code><code>##

sub each_iter(%) {
    my $hash = shift;
    my @keys = keys %$hash;
    sub {
        my $nkey = shift @keys;
        $nkey => $hash->{$nkey};
    }
}

my $iter = each_iter %some_hash;
while( my ( $k, $v ) = $iter->() ) {