my @list = qw/a b c d d a e b a b d e f/;
my @uniq = keys %{{ map {$_ => 1} @list }};
print "@list\n@uniq\n";
__output__
a b c d d a e b a b d e f
e f a b c d
####
map { $_ => 1 } @list
##
##
{ map { $_ => 1 } @list }
##
##
keys %{ { map { $_ => 1 } @list } }