Actually that is not quite right. If a variable is not visibly used in a returned subroutine, Perl cleans it up. You can verify that with this example: 
sub create_closure {
  my $x = "x";
  my $y = "y";
  return sub {
    $y .= "y";
    eval q{print "x: $x\ny: $y\n"};
  };
}

create_closure()->();

[download]
And you will find that $x is not properly remembered, but $y is.

In reply to Re^4: Syntax question about closures and Perl 'sort' by tilly
in thread Syntax question about closures and Perl 'sort' by dwm042

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