perl -MData::Dumper -le 'my %cubes = map { $_ => $_**3 } 1..4; print Dumper \%cubes'
$VAR1 = {
          '1' => '1',
          '2' => '8',
          '3' => '27',
          '4' => '64'
        };

my @users = [ {id=>4324, name=>'blah'}, {id=>1234, name=>'stuff'}, {id=>5678, name=>'foo'} ];
my %usersByName = map { $_->{id} => $_ } @users;
my $id = prompt_for_user_id;
my $user = $usersByName{$id};