Held: Wednesday, 2 March 2016

Back to Outline 22 - Images as Functions from Position to Colors. On to Outline 24 - Characters and Strings.

Summary

We explore further details of Scheme's lists. Lists are an important mechanism for structuring data. We also consider how lists can be used to represent drawings.

Related Pages

• Reading: Building Data Structures with Heterogenous Lists
• Lab: Building Data Structures with Heterogeneous Lists
• Reference: Important List Procedures
• EBoard 23 (Source 23)

Overview

• Lists, revisited.
• New list operations.
• Drawings as values.

Administrivia

• New partners!
• Prof. Curtsinger will be teaching class for the rest of the week.
  • If anyone wants to take notes for eboards, I'll provide extra credit.

Reminders

• No more office hours this week.
  • I'll do a lot of email or text Q&A this week.
• Tutor hours
  • Sunday, 3-5 p.m.
  • Sunday-Thursday, 7-10 p.m.
• Weekly review sessions:
  • Wednesday at 8pm in the CS Commons with ...
  • No Thursday review session this week .... )-:
  • Thursday at 8pm in the CS Commons with ...

Upcoming Work:

• Reading for Wednesday
  • Characters and Strings
• Exam 2 due next Tuesday.
  • Prologue due Friday night!
• Lab Writeup: Exercise _
  • Send email titled CSC 151 Lab Writeup 23 (Your Names)
  • Do not include the underscores.
  • Send to CSC151-02-grader@grinnell.edu
  • Due before class on Friday.

Extra Credit

• Send your reports to rebelsky@grinnell.edu with subject "CSC 151 Extra Credit". (Do not include the quotation marks.)
• Send opportunities to me before class with subject "CSC 151 EXTRA CREDIT OPPORTUNITY!"

Academic / Artistic

• Met Opera Simulcast, Saturday, March 5.

Peer

• Pub Quiz TONIGHT at 10, hosted by Neuro/Psych SEPC. You can eat food, or pay to participate in the quiz ($3/team).

Regular Peer

• Social Dance Workshop Tuesdays 7:00-8:00 in Bucksbaum Dance Studio
• Pun club Saturdays at 4pm in Younker
• Electronic Potpourri on KDIC Fridays at Five
• Space Odyssey KDIC Fridays at Six
• Fridays 7:30-8:30 Younker Lounge, Bollywood Dancing Team Fun Gathering

Misc

• Christine Tran show in Smith Gallery.
• Thursday evening Pub talk on Plans - Grinnell's own contribution to social media

Far in the Future

• Lords of the Flies, April.

No Extra Credit, But Still Good

• Vote in whatever runoffs there are. (Sorry, but one election is enough.)

Lists

• Our first encounters with lists.
  • Collection of values
  • Homogeneous: All the values in a list are the same type
  • Used primarily with map
• Extending that notion
  • Can also be heterogeneous: Values in the list may have multiple types.
  • Can examine individual elements with car, cdr, and list-ref.
  • Can be extended (creating new lists) with cons.
  • There's an empty list: null.
• Why is the new view important?
  • It will soon give us the opportunity to manipulate lists in new and interesting ways.

Implementing Drawings

• We can (and do) use lists to implement drawings.
• The reading considers a simplified representation, in which the width and height of a drawing are the same.
• But the general process is the same
  • Group the values in a list
  • When we need to render or manipulate a drawing, use the list operations to extract parts.

Lab