Overview

• Preliminaries.
  • Admin.
  • About HW 4.
• Context: What and Why Lists?
• Building Lists.
• Mapping Lists.
• Other List Operations.
• Lab.

Admin

• I realize that there's crud going around campus. Do yourself and your classmates a favor and get rest if you are sick. Drop me a note to let me know.
• Continue lab partners!
• I'm going to have an optional class this Thursday at 1:15 (and, I hope, most Thursdays) as a chance to talk to folks about more things that might be useful or interesting.
  • We won't have the optional class Thursday the 3rd, as I'll be unavailable.
• Work for Friday:
  • Review the homework assignment
  • Read Anonymous Procedures
  • Do lab writeup 5 if you haven't done so already.
  • Do Lab writeup 6: Exercise 5 from the Lists of Drawings Lab
    • Due before class on Friday.
    • Title: "CSC 151.02 Lab Writeup 6: Lists (NAME)".
• EC Opportunities:
  • CS Extras Thursday @ 4:30: Jennelle Nystrom on working at Microsoft
  • CS Table Friday (The Story of Mel)
  • Football, 1pm, Saturday against Beloit
  • Orchestra, 2pm, Saturday, Sebring-Lewis or somewhere similar
  • Folksyish music with Seth at Relish, TONIGHT at 10pm
  • Knitting club, Saturday at 10am. Do good and have fun!
  • More ...?
• Other things you might do (no EC, but possibly a good idea)
  • Facing the Bear, 7-9 pm Wednesday
  • Swipe your P-Card at the Football or Soccer game
  • Poweshiek CARES March Thursday. Leave from Herrick at 4:45 p.m. Email chenjerem@gmail.com for more info. I can also forward you the email.
  • Poweshiek CARES March Thursday, Oct. 3. Meet at Drake Library at 5 p.m.
  • GHS Homecoming Parade Thursday, Oct. 3. If you've never seen a small-town homecoming parade, it's worth it. (And last year's homecoming queen is a current Grinnell student.)

HW4

• We have a new homework assignment. The only thing my random procedure paid attention to was whether or not you asked to work alone.
• Yes, I can try for pairs on an assignment

Context: What and Why Lists?

• Collections of information
  • "Numbers between 1 and 10"
  • "Names of all the students in this class"
  • "A few drawings that I want to render"a
  • "A list of homework assignments to complete"
  • "A list of the valid colors"
• "List of things" is a new type
  • What do values look like? Syntax '(value value value) Looks a lot like a procedure call
  • How to make them? Constructors (list value value value value) (make-list num value) (iota num) -> 0 1 2 3 ... num-1
  • What procedures are available (append list1 list2) -> join together (reverse list) (take list n) -> First n elements of a list (drop list n) -> Drop first n elements
• These are non-mutating operations: The original list does not change

Mapping Lists

• Given a procedure and a list, you can apply the procedure to every value in the list
• You need lists
• They must be the same size

Lab