my(@a) = ();  # This declares a lexically scoped array and initializes 
              # it to be empty.

my($b) = {};  # This declares a lexically scoped scalar and initializes 
              # it to a reference to an empty anonymous hash.

my(@c) = [];  # This is probably a mistake. 
              # It declares a lexically scoped array and sets its 
              # first element to a reference to an empty anonymous 
              # array.

my(%d) = ();  # This declares a lexically scoped hash and initializes 
              # it to be empty.