I wanted to comment on style here. Notice that hippo writes

my @array = qw/b d a c/;

my %hash = (
    a  => 200,
    b  => 100,
    c  => 30,
    d  => 40
);
[download]

while Thanos offers

my @keys = qw(b d a c);
my @values = qw(200 100 30 40);

my %hash;
@hash{@keys} = @values;
[download]

I didn't know this trick with hash slicing, and I appreciate the pointer. It is very helpful to learn new things.

Stylistically, the latter is smart, the former is pleasant. If I can invoke Henry Koster's _Harvey_, "'In this world, Elwood, you must be oh so smart or oh so pleasant.' Well, for years I was smart. I recommend pleasant. You may quote me." These two aren't identical, I think. Note $hash{'a'} is different in the two samples (30 and 200). There are times when clever is better (more concise, more elegant, more insightful, golfing) and there are times when obvious is better. If I'm just writing for myself, I lean toward clever. But when I'm trying to get something done, or writing for myself in six months, I'm with Elwood.