my %foo;
@foo{qw/ foo bar baz /} = 1 .. 3;
printf "%%foo = %s { %s } = ( %s )\n",\%foo,scalar %foo,
       join(",",map "$_ => $foo{$_}",keys %foo);
while (%foo) {
    my $key = each %foo;
    my $val = delete $foo{$key};
    printf "%s => %s is gone.\n", $key, $val;
    printf "%%foo = %s { %s } = ( %s )\n",\%foo,scalar %foo,
           join(",",map "$_ => $foo{$_}",keys %foo);
}

##</code><code>##

%foo = HASH(0x1ab298c) { 2/8 } = ( foo => 1,baz => 3,bar => 2 )
foo => 1 is gone.
%foo = HASH(0x1ab298c) { 1/8 } = ( baz => 3,bar => 2 )
baz => 3 is gone.
%foo = HASH(0x1ab298c) { 1/8 } = ( bar => 2 )
bar => 2 is gone.
%foo = HASH(0x1ab298c) { 0 } = (  )