Further to LanX's reply:   Consider the two statements
    @ra = ({a=>1, b=>2}, {a=>1, b=>2});
and
    @ra = ({a=>1, b=>2}) x 2;
In the first, two different anonymous array references are being constructed. In the second, a single anonymous array reference is constructed and then repeated twice. 

c:\@Work\Perl\monks\tel2>perl -wMstrict -MData::Dump -le
"my @ra = ({a=>1, b=>2}, {a=>1, b=>2});
 print qq{@ra};
 ;;
 @ra = ({a=>1, b=>2}) x 2;
 print qq{@ra};
"
HASH(0x1555cdc) HASH(0x1555e50)
HASH(0x1555e20) HASH(0x1555e20)

[download]

In 

c:\@Work\Perl\monks\tel2>perl -wMstrict -MData::Dump -le
"my %hash;
 ;;
 @hash{ qw(key1 key2) } = ({a=>1, b=>2},{a=>1,b=>2});
 dd \%hash;
 ;;
 @hash{ qw(key1 key2) } = ({a=>1, b=>2}) x 2;
 dd \%hash;
"
{ key1 => { a => 1, b => 2 }, key2 => { a => 1, b => 2 } }

do {
  my $a = { key1 => { a => 1, b => 2 }, key2 => 'fix' };
  $a->{key2} = $a->{key1};
  $a;
}

[download]
the  do { ... } business with the  'fix' in the second dd instance just reflects the fact that a hash reference  $a is built that needs to have its  'key2' key "fixed" later by a  $a->{key2} = $a->{key1}; statement that makes the value of 'key2' the same as 'key1': they're the same reference. (Update:  dd works by generating source code that | source code text that, when run thru eval, will reproduce the structure of the data being dumped.)

Update: Clarified the update remark about  dd per LanX's comment here. Thanks, LanX!

Give a man a fish:  <%-{-{-{-<

In reply to Re^7: Combinations of lists, etc by AnomalousMonk
in thread Combinations of lists to a hash by tel2

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