CSC 151.01, Class 03: Basic types

Retain partners and places from Monday (before the chaos)!

Overview

• Preliminaries
  • Notes and news
  • Upcoming work
  • Extra credit
  • Questions
• Finish Monday’s labs.
• New lab.
• Debrief.

News / Etc.

• I’ll take attendance in a hope of starting to learn names.
• Thank you to all of those who let me know about broken links and such in the course Web site. I’m doing my best to catch problems and fix them. It helps to have others help catch them, too.

Stuff due

• Signed academic honesty policy.

Upcoming Work

• Quiz Friday: Parts of algorithms, basic Scheme.
• Read: Making and manipulating simple lists
• Read: How Scheme evaluates expressions, take 1
• Assignment 2 due next Tuesday.
  • Today’s lab partner is your homework partner.

Extra credit (Academic)

• Rosenfield Internship Talks, Thursday at 11 a.m. in JRC 101.
• Writers@Grinnell Roundtable, Thursday at 4:15 in JRC 209.
• Writers@Grinnell Reading, Thurday at 6 p.m. in the Pioneer Bookshop.
• Rosenfield symposium, next week. (Lots of different events)

Extra credit (Peer)

• Women’s Soccer vs. Simpson, Friday, 5:00 pm, Springer Field
• Women’s Soccer vs. Alumnae, Sunday, Noon, Springer Field
• Men’s Soccer vs. Coe, Friday, 3:00 pm, Springer Field
• Men’s Soccer vs. Alumni, Sunday, 2:00 pm, Springer Field
• Volleyball vs. Wisconsin-Whitewater, Friday, 4;00 pm, Coe College (Cedar Rapids)
• Volleyball vs. Wisconsin-La Crosse, Friday, 8;00 pm, Coe College (Cedar Rapids)

Extra Credit (Misc)

• Community Hour (Dialogues Across Difference), Tuesday at 11 a.m. in JRC 209.
• CLS Kick-Off Event, Tuesday at 11 a.m. in “North Campus Grove”

Good things to do

• Ag Days in Grinnell, Thursday the 31st.

  The Grinnell Lions Club is sponsoring Ag Appreciation Day, Thursday, August 31 from 3 to 7 pm. Vintage tractors, demonstrations, family fun, tractor parade, food & games, and live music by Route 66 from 4-6pm. Bring the family! Free admission. Ag Day was started over twenty years ago as a way to bring farm families, agribusiness, and community members together to recognize and celebrate all forms of agriculture and agribusiness as a major economic force in the greater Grinnell area.

Questions

Finish Monday’s labs

• Linux
• Getting started with Scheme

Start new lab - Types

• Note: The reference pages for the various types are not yet up!

Writeup

Your writeup is exercises 2h and 10. Due Friday night. Sooner would be better.

• Email to csc151-01-grader@grinnell.edu.
• Subject: CSC 151 Writeup for Class 3 (Name1,Name2)
  • E.g., CSC 151 Writeup for Class 3 (Clingy,Fallenangel)

Debrief

Assorted Comments

• Remember: Computers are sentient and malicious!
• Some of those random incantations are important, such as raco link ....
• DrRacket may be even more annoyingly precise than I am. For example, if the file on the Desktop does not have a .rkt suffix, the require command will not work.
• Read the error messages. They may not make complete sense, but there could be something helpful along the way.
• Scheme (DrRacket) is stupid. It doesn’t know context.
  It doesn’t know about relationships. It just knows how to compute. (square (sqrt 2)) is pretty obviously 2. But, DrRacket computes (sqrt 2), which it approximates.
• You often learn about a new procedure by trying different arguments (e.g., the examples for remainder).

A Dialogue

Sam, should we write stuff down?

I don’t know. Will you remember stuff if you don’t write it down?

Probably not.

I think you’ve answered your own question.

Questions from students

Can we work at home (or elsewhere)?

We would not recommend it for most of your work, at least at first.
There’s a benefit to being here and having people around.

You can download DrRacket from the Interweb for almost any desktop platform (Microsoft Windows, macOS, most Linices). Search for “Download DrRacket”.

I like the gridded post-it pad. Can I take one or two?

Yes.

Questions from SamR

What did you see as the differences between floor, ceiling,

truncate, and round?

truncate chops off the decimal portion

floor rounds down

Why might the following happen?

> (round 2.5)
2.0
> (round 3.5)
4.0