Recursion -- A Summary

(1) Easy to code up when the intrinsic recursiveness is seen:

  n!    fib(n)    ack(m, n)
  length (list)   print (list)
  postfix(tree)
  
(2) For concurrency, recursion is good because each function call causes a
separate stack frame, so that data is protected from uncontrolled access.

(3) Recursion is usually more expensive in performance: It takes longer to
push/pop stack frames than to iterate.

(4) To improve performance of recursion:
   a) Rewrite to iterative implementation
   b) Convert to tail recursion if possible. The compiler can optimize tail recursion.
   c) Memo-ize