Held: Monday, 22 February 2016

Back to Outline 16 - Programming the GIMP Tools. On to Outline 18 - Conditionals.

Summary

We consider the ways in which Scheme supports yes/no questions and procedures that can be used to ask such questions. We also see how such procedures can provide another form of control.

Related Pages

• Reading: Boolean Values and Predicate Procedures
• Lab: Boolean Values and Predicate Procedures
• EBoard 17 (Source 17)

Overview

• Boolean values.
• Predicates - Procedures that return Boolean values.
• Combining booleans with and and or.

Administrivia

• New partners!
• Sam is incredibly behind on grading. Quizzes returned tomorrow. Exams may take another week.
• We'll talk a little bit about testing.

Reminders

• Office hours: MTWF 10-11, Tu 1-2.
  • Sign up at http://rebelsky.youcanbook.me.
  • Also feel free to stop by when my door is open.
  • Or to email me for an appointment.
• Tutor hours
  • Sunday, 3-5 p.m.
  • Sunday-Thursday, 7-10 p.m.
• Weekly review sessions:
  • Wednesday at 8pm in the CS Commons with
  • Thursday at 10am in this room with SamR
  • Thursday at 8pm in the CS Commons with

Upcoming Work:

• Reading for Tuesday
  • Conditionals
• Assignment 4 due Tuesday night at 10:30 p.m.
• Lab Writeup: Exercise _
  • Send email titled CSC 151 Lab Writeup 17 (Your Names)
  • Do not include the underscores.
  • Send to CSC151-02-grader@grinnell.edu
  • Due before class on Wednesday.

Extra Credit

• Send your reports to rebelsky@grinnell.edu with subject "CSC 151 Extra Credit".
• Send opportunities to me before class with subject "CSC 151 EXTRA CREDIT OPPORTUNITY!"

Academic

• Monday's Data on Students Presentation, noon, JRC 101, with lunch
• Sexual Assault Awareness Week Discussion, Monday, 7:30 pm JRC 101
• CS Table, Noon, Tuesday, White PDR.
• State of SHACS Discussion, Tuesday, 7pm JRC 209
• Town Hall, Wednesday, noon or 7:30 pm (I think) JRC 101

Peer

• Pun Club Tournament Friday the 26th in the evening.
• Contra Dance Friday the 26th in the evening.
• Improv Show the 27th in the evening in Loose Lounge.

Regular Peer

• Social Dance Workshop Tuesdays 7:00-8:00 in Bucksbaum Dance Studio
• Pun club Saturdays at 4pm in Younker (max 2)
• Electronic Potpourri on KDIC Fridays at Five (TONIGHT)
• Space Odyssey KDIC Fridays at Six

No Extra Credit, But Still Good

Preparation

• What did you learn from the reading? (Let's try to summarize for each other.)
• What questions do you have?

or and and as control structures

• How does normal procedure application work?
  • Evaluate all the parameters
  • "Plug them in to the body"
  • Evaluate the body
• How does or work?
  • It evaluates each parameter, in turn, until one holds (or it runs out of parameters).
  • As soon as one holds, it stops and returns that value.
• How does and work?
  • It evaluates each parameter, in turn, until one fails to hold (or it runs out of parameters).
  • As soon as one fails to hold, it stops and returns #f.
• This evaluation strategy means that we can use and and or to evaluate a sequence of expressions, stopping when we get the first acceptable one.

Lab

• Work on the lab
• Be prepared to discuss!