racket recursion 2.9/4 --- memoization with recursion
Channel: Danny Heap
Date: 2012-06-01

Video from http://www.cdf.toronto.edu/~heap/racket_lectures.html.  Recursion is the obvious choice for implementing a function that is recursive, such as the fibonacci sequence.  However, sometimes a naive recursive implementation forces a computer to re-compute the same values *many* times.  The solution is to record each value the first time it's computed, and then look it up --- memoization.  See also

www.cdf.toronto.edu/~heap/Racket/recursion.html    More videos:
www.cdf.toronto.edu/~heap/racket_lectures.html