CSC151.02 2013F, Class 34: Pairs and Pair Structures
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_Overview_

* Preliminaries.
    * Admin.
    * Thinking about next semester.
    * Thinking beyond next semester.
    * Questions on exam 2.
* Representing lists: Pairs and cons cells.
* Why care about the underlying representation?
* Lab.

Preliminaries
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### Admin

* No writeup for today!
* New lab partners.  Choose your own, but it can't be someone you worked with
  last week!
* Upcoming extra credit opportunities:
    * Any one Grinnell prize event this week.
    * Thursday extras this week: Reports from internships (I think)
    * Grinnell Town Hall Meeting, Nov 13 noon or 7:30, I believe
    * CS Table, Friday: TBD
    * One love your body week event
    * Orchestra concert Saturday at 7:30 in Sebring-Lewis

### Going on in CS

It's almost time for preregistration.  Are you enjoying CS?  You should
continue.

* CSC 161, Imperative Problem Solving, is the next course.  
    * It focuses on on something closer to the Turtle model
    * That is, in 161 we worry much more about sequencing operations and
      we worry about the state of the system.
    * In 161, we also look much more "behind the scenes" (somewhat like
      what we're doing today).
    * 161 uses C as the programming language.
* MAT/CSC 208, Discrete Structures, is also useful.  It introduces
  you to some of the mathematics you need to better understand and
  analyze algorithms and data structures.
* CSC 195 is my "pre-research" course, but it's open to all comers.

### Thinking Ahead to the Summer

It might also be worthwhile to start thinking about next summer (whether
or not you are continuing in CS).  You only get three summers of college,
so you should make the most of them.

* I'll tell you a story one of my colleagues told me.
* It sounds a bit too practical for Grinnell, but you should use your
  summers well.
    * Explore potential directions (it's fine to have many, but the only 
      way to narrow is to explore).
    * Build skills.
    * Build your resume.
    * Of course, you should also destress and such.
* If you're interested in CS, you should go to this week's CS extra
   and the week 14 CS extra on "Summer Opportunities in CS".
* In any case, you should make the time to visit with the CLS.

### General Exam Questions

* Make sure to use a suffix of .rkt
* Don't comment out with boxes

Representing lists: Pairs and cons cells
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* When you write (cons a b), what does Scheme do?
Why care about the underlying representation?
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Lab
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