This is probably just a minor nit, but thought I might learn something. My understanding is that there is very little difference (from the perl interpreter standpoint) between:

my %hash = ('a', 'b', 'c', 'd');
[download]

my %hash = ('a' => 'b', 'c'=> 'd');
[download]

Advantages I can think of for the first representation are:

• As long as you know that a list has an even number of elements, you can use it as a hash.

The advantages I can think of for the second representation are:

• The => reads better from a maintainability standpoint
• you don't have to quote the key. For example:
  my %hash = (a=>'b', c=>'d');

Essentially => is syntactic sugar for ,.

Update. Missed a tic.