CSC151 2009F, Class 18: Iteration

Admin:
* Does anyone need a group for Assignment 4?
* Are there any questions on that assignment?
  * Why does map say "the list sizes need to be the same"
* We'll go over a few things on the quiz.
* I was not able to get the exam graded for today.  
  * Hence, we'll start on the next topic (iteration) today 
  * We'll go over the exam later in the week.  
    * I'm hoping to do it tomorrow.
    * But I have it scheduled for Friday, so that we're set on the next
      readings if I can't get everything done.
* On that note, the reading for tomorrow is 'Local Bindings with Let'
* Starting today, I'd like you to work with someone new 
  * Pick someone you have not worked with previously.
* I will not have office hours on Wednesday at 11:00.  
  + I will try to be available on Wednesday afternoon.

Overview:
* A Problem: Drawing Spirals
* A Useful Tool: for-each
* Another useful tool: sequence

A Problem: Drawing spirals
* Basic strategy: Go forward a little, turn a little, go forward a little,
  turn a little
  * Could use repeat, but if the distance and angle stay consistent,
    we get a circle, not a spiral
  * We could change the distance every bit (good job to that group!)
* for-each is the alternative to map that lets you 
  * do things in order from left to right