• New partners!

Overview

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

Preliminaries

Admin

• Exam 2 answer key distributed last night.
• Review sessions this week:
  • Wednesday, 8pm (Caleb)
  • Thursday, 10am (SamR)
  • Thursday, 8pm (Erin)
• In yesterday's discussion of repetition, I forgot to mention two map-like procedures: (all pred? lst) and (any pred? lst). They do what you'd expect.
• Why don't you use the evening tutors?
  • It's more productive to send Sam email.
  • Some of them are not familiar with the problems, so you have to explain the problems.
    
    • We need to make sure that the tutors know the current assignments.
    • There is some advantage to explaining.
  • I'm not in the lab.
  • Hard to tell who they are. We should force them to wear a stupid hat.
  • Different tutors have different Scheme skills. Alex G has mentored this class twice
  • Our classmates are so awesome that we often go to them for advice, even through facetime.
  • Let's introduce the tutors to each class.

Upcoming Work

• Reading for Friday: Pairs and Pair Structures
• Exam 3 distributed.
  
  • Corrections and questions are now welcome.
• Quiz 9 on Friday.
  • Named let and letrec.
  • Turtles.
  • Iteration: repeat and for-each.
• Today's Lab writeup (due before class Monday)
  • Email to grader-151-01@cs.grinnell.edu
  • Subject: CSC 151 Lab Writeup Class 36 (Your Names)
  • Exercises: 3d or 4a

Extra Credit Opportunities

• If possible, send me these in advance.

Academic

• Any visit to the current show in the Faulconer gallery.
• Learning Deconstructed Workshop Series, Tuesdays at 11 in JRC 209. I hear that the first session was very useful.
• Any activity with Visiting Musician and Sound Artist Ellen Fullman. (Yes, that includes Drinks @ Lonnski's on Thursday.)
• Convocation Thursday: The US Labor Market is a Mess.
• CS Extras Thursday: Bluetooth, Robots, and CS 161.
• Sexual Misconduct at Grinnell College: Results from the 2013 and 2015 Sexual Conduct Surveys. 1-3 pm, November 8, JRC 101.
• CS Table next Tuesday.

Peer Support

• EC for ISO Food Bazaar. Sam will reimburse the $10 if you feel that it's a financial stretch. Tickets are on sale today, 11-1, 5-7. ISO Food Bazaar is Nov. 15, 5-7 pm. In Harris Gym/Concert Hall.
• Maybe an Alumni Game for Womens Basketball.

Regular Peer Support

• Pals of PALS, pals@grinnell.edu, normally Saturday at 7:45 am (breakfast included; felines only) and Mondays at 4:45. Requires sign up in advance. PLEASE SIGN UP! More help is needed, and it's a de-stressor.
• Socrates Cafe', Saturdays, Younker, 2pm.
• Pun Club, Saturdays, 4pm, Way over Younker.

Upcoming Peer Support

• November 14, Orchestra Concert, Sebring Lewis, 7:30 p.m.
• Women's Basketball Opening Game, 1 pm, Nov. 15, vs. Silver Lake.
• One-act Festival Dec. 5 & 6.

Questions

Can we look at any and all?

> (all odd? (list 1 3 11 23))
#t
> (all odd? (iota 5))
#f
> (any odd? (iota 5))
#t
> (any odd? (list 'sam 'erin 'zachary))
. . lib/gigls/higher.rkt:44:13: odd?: contract violation
  expected: integer
    given: 'sam
> (all odd? null)
#t
> (any odd? null)
#f
> (all even? null)
#t
> (all weird? null)
. . weird?: undefined;
cannot reference an identifier before its definition

• ES says: all goes through the list until it finds something false. If it never finds anything false, it returns true. Hence, (all odd? null) should be true. (Similar argument for any.)

Lab

For the pair-a-dice problem, you may find it helpful to write

    (define tally-seven-eleven
      (lambda (n)
        (display (list "tallying" n "more dice")) (newline)
        ...))

Writeup is 3d or 4a