CSC151.01 2015S, Class 23: Revisiting Lists
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* Continue partners.
* Food? (Optional!)

_Overview_

* Preliminaries.
    * Admin.
    * Upcoming Work.
    * Extra Credit.
    * Questions.
    * Quiz.
* Lab.

Preliminaries
-------------

### Admin

* Review session Monday at 7:00 p.m.
* Office hours today at 10:00 a.m.
    * <http://rebelsky.youcanbook.me>
* One of your classmates passed along the following article which you
  might find interesting. 
    * <http://www.wired.com/2015/02/science-one-agrees-color-dress/>
* Prospies Monday!  Be prepared for special activities.
* Friday PSA
    * In making choices this weekend, please make sure that Nobody Gets
      Hurt (including you).
    * There are a lot of illnesses going around campus.  Rest will help
      you avoid them better than almost anything.  (I'm telling myself
      the same thing.)

### Upcoming Work

* [Homework 6](../assignments/assignment.06.html) is optional so that
  you have time to get rest.
    * Due Tuesday at 10:30 p.m.
    * It will make up for one other homework assignment, provided it
      is higher than some other homework assignment.
* Exam 2 to be assigned on Tuesday.
* No lab writeup for today.
* Reading for Monday: Recursion Basics
    * [Recursion Basics](../readings/recursion-basics-reading.html)
    * A cool and different topic that we'll be talking about through
      spring break (and the rest of the semester).
* Fun with HW5
    * Create a large list of numbers (iota 1000)
    * Convert each number to an (x,y) coordinate
      (lambda (i) (mod (* 11 i) (image-width)))
      (lambda (i) (mod (* 13 i) (image-height)))

### Extra Credit Opportunities

#### Academic 

* CS Table Friday - Art, CS, and Artificial Intelligence.

#### Peer Support (Morning Section)

* Julia's radio show, "The Hot Box".  Wednesday night/Thursday morning 
  1:00-2:00 a.m.  
* Host a prospie.
* Indoor Track today and Saturday. Support Grinnell Pride!
* Neverland Players Friday and Saturday at 7:00, Sunday at 1:30 and 7:00
* Grinnell Singers Sunday at 2pm.  Handel's Esther.  Maybe Sebring Lewis.
* Orchestra a week from Saturday at 2pm in Sebring-Lewis.  Musicals and
  Show Tunes and Soloists.

### Questions

### Quiz

* When you're done with the quiz, bring up the lab, read through it, and
  wait for your partner.

Lab
---

* Pairs (`cons`) can be used to build lists, but they can also be used 
  to build things that aren't lists.
* If you have something that seems to be a list, but has a period in the
  middle, it's not a list.
* Since Erin seems to enjoy stupid wordplay, we used to use the following
  names for the values in problem 3: `one-two`, `won-too`, `want-to`.
* Pronounciation: 
   * "cdr" = "could-er" or "cudder"
   * "cadr" = "cahd-er"
   * "cddr" = "could-ood-er"
   * "car" = "cah"

Learning Outcomes
-----------------

* We can manipulate lists with `cons`, `car`, and `cdr`
* Computer scientists count starting at 0.
* Lists provide mechanisms for storing collections of related data.
    * Characteristics of a shape.
    * Ratings of a movie.
    * Information on a course at Grinnell.
    * Etc.
* If you know the form of the list, you can work with the data.