I'm puzzled by this

sub foo {
   #  vvvv Temp array
   my @ret = map {
      # body of foo here
      $whatever;
   } @_; # <<< list 1

   #    vvvvvvvv list 2
   @ret[0..$#ret];
#  ^^^^^^^^^^^^^^ list 3
}
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Why generate one temporary array and three lists to achieve the same effect as

sub foo {
   map {
      # body of foo here
      $_[ $_ ] ...;
      $whatever;
   } 0..$#ret;
}
[download]

which creates 2 lists and no temporary array.

What am I missing?