#!/usr/bin/perl -CSDA

use utf8;
use Modern::Perl qw{2017};

use Data::Dumper;
$Data::Dumper::Sortkeys = 1;

my $h = {a => 1, b => "", c => 2};
my $d1 = Dumper($h); 

printf "grep: %s\n", (join " ... ", grep { $_ }  $$h{a}, $$h{x}, $$h{b}, $$h{c});

printf "test: %s\n", $$h{y} ? "yes" : "no";

my $d2 = Dumper($h); 
$d1 eq $d2 or  die "\nFAIL! h{x} modified, h{y} not modified... why?\n\n$d1\n$d2";