CSC153 2004S, Class 41: Scheme Lists

Admin:
* Homework 6 due.
  * Should Saul turn in crap today or better stuff tomorrow?  It's up to Saul.  Maximize (gradeFor(crap) vs. gradeFor(notCrap)-10points)
* "Computers in the Humanities" talk Friday at noon in 2424.  Free pizza!  Extra credit!
* Visitor Friday.  Fun fun fun!
* Exam 3 distributed.
* Sam's work queue:
  * Finish sample code for CSC362
  * Plan for Friday's talk
  * Do reading for Friday's TEC154 class
  * Plan Friday Tutorial talk
  * Clean office slightly
  * Grade CSC153
* Saul has a story ... Once upon a time, Saul decided to show up for his PolySci class.  Moral: It sucks to be a Grinnell teacher.

Overview:
* Scheme lists

/Scheme lists/
* Basic idea: A series of things; 
* Key operations: car, cdr, cons, null, null?
* Applications already known
* Implementation: A bunch of pairs, the second element of which points to the next pair
* How do we represent the key operations in Java *without focusing on implementation*  See SchemeList.java
* What's the difference between an interface, an abstract class, and a class
  * Class: Can include
    * constructors
    * object fields
    * class fields
    * object methods (which must be defined)
    * class methods
    * destructors
  * Interfaces: Can only include
    * headers of object methods
  * Abstract classes: A compromise
    * Like classes
    * Not all methods need definitions/some can just have headers
* Classes can only extend from one class
* Classes can implement multiple interfaces