As shown by its data dumper output, $data_b is a reference to an array. The referenced array has a single element: a reference to a hash with four elements as shown.
Assuming a successful operation to merge the contents of the hash referenced by $data_a, what would you then want the data dumper output of $data_b to look like?
Update: The Perl Data Structures Cookbook (perldsc) may prove helpful now and in the future.
Give a man a fish: <%-{-{-{-<
In reply to Re^5: Add array ref to another array ref
by AnomalousMonk
in thread Add array ref to another array ref
by Anonymous Monk
| For: | Use: | ||
| & | & | ||
| < | < | ||
| > | > | ||
| [ | [ | ||
| ] | ] |