in reply to Re^2: Massive expansion of a hash of arrays?
in thread Massive expansion of a hash of arrays?

I recommend you start with the Wikipedia article titled Recursion (computer science). And because "recursion is one of the central ideas of computer science," you're going to find explanations and examples of it in any good computer science textbook.

If you have an arbitrarily nested data structure with both arrays and hashes in it, then you're going to need to use the ref function. You'll use an if-then-else construct within your recursive function to decide what to do at each level in the nested data structure.