If you understand recursion, you are free to go, otherwise, reread this sentence.

Years ago I picked up how to use a Stack or Queue (C#) to traverse a hierarchy and have never used a recursive function since (because the are the bane of any debugging effort).

@monkeyboy on the other side, most of the recursive logic I write in a language like Haskell (or even in C++/C#) barely requires debugging. As a general rule, recursion and pure functions work really well, side effects create problems because they impose things like orderings. Recursion is a great tool and one must know when and how to use it properly, just avoiding it altogether is not exactly the best way to do things.