I interpreted what NetWallah wrote as assuming the OP might want to do something more than what was posted and offered a suggestion. I know chromatic is a smart guy, so if he had meant - you shouldn't be transforming here, you should just be filtering (map vs grep) then I understand the comment. But the code block as written, which I am sure NetWallah understood is most naturally written as map not grep (at least to me) is what chromatic appeared to be responding to (at least to me). That is why I asked for elucidation. Your response, which is a legitimate interpretation of comment - is not what I took away. Especially given it was so terse.

I interpreted what NetWallah wrote as assuming the OP might want to do something more than what was posted

Me too. Why skip entries with no emails if you're not going to use the emails?

I could see

my @emails = map { $_->{email} eq '' ? () : $_->{email} } @$data;
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although it might be clearer to do

my @emails = grep $_, map $_->{email}, @$data;
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I just saw these updates. Thanks for coming to my defense!

The strange thing is - when I read chromatic's question, and re-read my code a day later, I did have to re-think for a minute about why I used map instead of grep. You were spot-on.

     Syntactic sugar causes cancer of the semicolon.        --Alan Perlis