Here's an even shorter way, if you don't want to use a variable at all:
my @uniq = keys %{{ map { $_ => undef } @proc_name1 }};
However, this is slower than the slice and grep methods, both.
use strict;
use warnings;
use Benchmark q{cmpthese};
my @arr = ( q{a} .. q{z} ) x 1_000;
cmpthese(
-10,
{
useGrep => sub {
my %seen;
my @out = grep { !$seen{$_}++ } @arr;
return @out;
},
useSlice => sub {
my %seen;
@seen{@arr} = ();
my @out = keys %seen;
return @out;
},
useRef => sub {
my @out = keys %{ { map { $_ => undef } @arr } };
return @out;
},
}
);
Rate useRef useGrep useSlice
useRef 74.3/s -- -64% -84%
useGrep 204/s 175% -- -56%
useSlice 464/s 525% 127% --
(Thanks to johngg for the tests in Re: to select unique characters).