if some kind soul would give an explanation of why the third antirice loop works, i could sleep easy. easier...

foreach my $key ( @{[%hash]} ) {
 print $key;
 delete $hash{$key};
}
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What antirice has done here is to take a copy of the hash as a list. After this, interating over the copy means that every second delete attempts to delete a key that never existed in the hash and fails quietly while all the others succeed.

No doubt you're confused by the

@{[%hash]}
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bit.

Enclosing something in square brackets in Perl takes it in list context. It also generates an array reference to that. So %hash here is copied into an annoymous array. This is then deferenced by the @{}s because foreach expects a list, not a reference.

Does this help?

All the best,

jarich