perl - Is hashref in array?

[Alan Young]

Hill, Greg wrote:
> Can't you just do:
> 
> my %seen = ();
> my @unique = grep { !$seen{$_}++ } @tree;

Actually this would be more efficient (and perlish):

my @unique = do { my %s ; @s{ @trees } = '' ; keys %s };

> Or am I missing something?

Yeah.  He was getting the stringified reference (HASH(0xABCDEF)) as a 
key and he wanted the actual data as a key.  So you have to serialize 
the referenced data for each key and have some way of bringing it back 
as a reference of values.