Re: Perl Idioms Explained - keys %{{map{$_=>1}@list}}

[Aristotle]

Just as memory hungry, still not order preserving, and still broken with regards to undefined values, but faster approach:

my %seen;
@seen{@list}=();
my @uniq = keys %seen;

And if you want to wrap it up without "leaking" lexicals:

my @uniq = do {
    my %seen;
    @seen{@list}=();
    keys %seen;
};

This approach does not (explicitly) iterate - more of the data structure setup work is done implicitly by perl.

Makeshifts last the longest.