Linked lists have a gotcha in perl. If you implement them with references, you can easily create cycles which perl cannot destroy. That happens because each element's refcount is held up by its predecessor. That is easily handled with a DESTROY method which breaks the cycle by overwriting the reference to successor with other data.

In recent perl, it is possible to use weak references to avert the problem.

I like the idea of using Graph for the sort of thing you're doing.

After Compline,
Zaxo