Hi,

Its because hashes have only one internal iterator

my %hash = 1..4;
my $stop = 0;
while( my( $k, $v ) = each %hash ){
   $stop++;
   print "# $k $v\n";
   while( my( $kk, $vv ) = each %hash ){
       print "## $kk $vv\n";
   }
   die if $stop > 2;
}
__END__
# 1 2
## 3 4
# 1 2
## 3 4
# 1 2
## 3 4
Died at - line 9.
[download]

First loop's each starts the iterator,

The second loop's each continues the iterator until the end is reached, when the iterator resets

then the first loop's each starts iterator again

Iterator can also be reset with keys

$ perl -le" %f=1..4; while( each %f ){print $g++; } "
0
1

$ perl -le" %f=1..4; while( each %f ){print $g++; keys %f; die if $g >
+ 5; } "
0
1
2
3
4
5
Died at -e line 1.
[download]

YAML::Syck::DumpFile uses keys/each in order to copy the hash, thus it ends up resetting the internal iterator

Maybe you want to dump the $v variable instead of the $hash? Or just dump the $hash outside of a loop?