debugging: logging / print when new function call added to cache?

[cmwetherell]

Does this feature already exist? I'm trying to figure out why memoization is not speeding up my recursive function call and I think this would be a useful feature.

Aside from that, I think I might not be getting much improvement because my recursive call never completes any of the recursive trees until they're all done. I'm fairly new to recursion and memoization, as you might be able to tell :)