• New partners!

Overview

• Preliminaries.
  • Admin.
  • Upcoming Work.
  • Extra Credit.
  • Questions.
• Lab.

Preliminaries

Admin

• Review sessions
  • Wednesday at 8pm (Kumar)
  • Thursday at 10am (SamR)
  • Thursday at 8pm (Erin)
• Graders finally starting to send you things.
  
  • Lots of gaps in the early labs. I'll look at these issues over the weekend and suggest a solution on Monday.
• I'll send out a summary of grades on Sunday night.

Upcoming Work

• Optional Re-Reading for Friday: Anonymous Procedures
• HW 5 due Tuesday
  • To be released tonight
• Today's Lab writeup (due before class Monday)
  • Email to grader-151-01@cs.grinnell.edu
  • Subject: CSC 151 Lab Writeup Class 20 (Your Names)
  • Exercise: 5d and 6b
  • Warning! Sam just rewrote the lab.
• Quiz Friday
  • Homogeneous lists and map (know section and o for map)
  • Drawings as values
  • GIMP Tools
  • if, when, and cond

Extra Credit Opportunities

• If possible, send me these in advance.

Academic

• Any visit to the current show in the Faulconer gallery
• EE's show in Smith (closing tonight at 8pm)
• Convocation tomorrow at 11am
• Peter Coyote talk 7pm Thursday
• Liz Queathem talk 4pm Friday
• MET Livecast Saturday at noon at Harris Auditorium
• Peter Coyote workshop on Saturday 10-12 and 1-4

Peer Support

• Pals of PALS, pals@grinnell.edu, normally Saturday at 7:45 am (breakfast included), Sunday at 4:45, and Mondays at 4:45. Requires sign up in advance.
• PALS dinner Thursday night. (Sam will treat if you find it a financial burden.)
• Pun Club, Saturdays, 4pm, Way over Younker.
• Mid-Autumn Festival, Saturday, Oct. 3, 6-8 p.m. in Harris Concert Hall.

Other Good Things (No EC)

• VBall Saturday at 1pm in Darby
• American Football Saturday at 1pm at the football field
• Women's Unamerican Football Saturday at 11am
• Men's Unamerican Football Saturday at 1pm
• Women's Soccer Sunday at 11am
• Men's Soccer Sunday at 1pm
• Grinnell-Link Networking Reception Friday at 4:45pm JRC 2nd Floor Lobby

Questions

Lab

Other than these stupid problems, why would we use let outside a procedure? (EG)

It's rare that we do so, but it's something useful to know. See extra 1 for an example.

For those of who are puzzled by bindings, can you give us some more questions?

What do you get for the following?

    (define alpha 3)

    (let ([alpha 5]
          [beta (+ alpha 1)])
       (list alpha beta))
    ; '(5 6)
    ; '(3 6)
    ; Error!
    ; '(3 4)

    (let* ([alpha 5]
           [beta (+ alpha 1)])
       (list alpha beta))

    (let ([delta 5]
          [epsilon (+ delta 1)])
      (list delta epsilon))

Why would someone change an existing procedure?

Sometimes your users are evil.

What is the lab writeup?

5d and 6b