1. Why take CS1101S? (or why Scheme?)
Ben Leong
NUS School of Computing
24 July 2009

2. NOT to teach you Scheme 
Welcome to SoC
Help you make an informed decision on whether to choose between CS1101 and CS1101S
NOT to teach you Scheme 
About which class is more suitable for YOU
NOT about which is better….

3. Overview What your seniors say What’s Scheme? Why Scheme?
Module Synopsis
(i.e. what to expect)
What your seniors say

4. Brief History of CS1101S
The language Scheme was designed 28 years ago at MIT to teach programming methodology
The success of the MIT programming methodology module led to its adoption in many universities worldwide
Scheme was first introduced at NUS 12 years ago
I took this class at MIT in 

5. Computational Thinking
Objectives
Teach Scheme as a programming language
Teach programming concepts
Inspire CONFIDENCE in students that ANYTHING can be solved if they try hard enough
Teach students
Computational Thinking
NOT!
TO THINK 

6. What is Scheme?
Scheme is expression-oriented. Type an expression and its result will be printed out.
Works with a variety of types of numbers: integers (both positive and negative), fractions (rational numbers), and real numbers

7. What is Scheme? Expressions use prefix notation.
Use (+ 2 3) instead of (2 + 3)
Use (* (+ 2 3) (- 3 1)) instead of (2+3)*(3-1)
There is a wealth of predefined functions
sqrt computes the square root of its argument.
+ is also a predefined function

8. Why Scheme? Teaching a language is futile (Here today, gone tomorrow)
Scheme is simple as a language
So we can focus on the CONCEPTS instead of clunky language rules
Let’s see for ourselves…..

9. Key Concept: Recursion
Express (divide) a problem into smaller similar problems
Solve the problem for a simple (base) case
We are done (!)
Similar to
Mathematical Induction

10. The Towers of Hanoi
We have 3 pegs and a set of discs, all of different diameters.
Objective: move the pile of discs to last peg, by:
moving 1 disc at a time from 1 peg to another;
never placing a disk on top of another disc with smaller diameter.
Suppose you have not 3, but n discs …

11. We must start somewhere…. Suppose we have one disc ….
The Towers of Hanoi
We must start somewhere….
Suppose we have one disc ….
What if there are no discs?
Nothing to do!
Base case

12. The Towers of Hanoi RECURSION
We notice the following pattern: if we want to move n disks from peg a to peg c using peg b as intermediary storage, then we:
assume we know how to move n−1 disks to peg b, using peg c as intermediary storage;
we move disk n from a to c ;
we move n−1 disks from b to c, using a as intermediary storage.
RECURSION

13. The Towers of Hanoi (define (move-tower size from to extra)
(cond ((= size 0) #t)
(else
(move-tower (- size 1) from extra to)
(print-move from to)
(move-tower (- size 1) extra to from))))
(define (print-move from to)
(newline)
(display "move top disk from ")
(display from)
(display " to ")
(display to))

14. DEMO

15. CS1101S: Programming Methodology (Scheme)
Lectures:
Wed 10am-12pm, Fri 11am-12pm, LT15
Recorded for webcast
Recitations: 1 hr/wk
Two or three groups: Prob Thurs, Venue TBA
Discussion Groups: 2 hr/wk
Three or four groups: TBA
Bid for group in CORS

16. Teaching Staff
Lecturer: Dr. Ben Leong, Office: S14 #06-14
Phone:
Hours: TBA, or by appointment
Teaching Assistant: Chu Duc Hiep
FIVE Undergraduate Discussion Group Leaders

17. CS1101S Road Map Java Fundamental concepts of computer programming
Memoization
Streams
ADVANCED
Dynamic Programming
Object-Oriented Programming
INTERMEDIATE
Symbolic Data
Higher-Order Procedures
List Processing
Generic Operators
BASIC
Data Abstraction
Mutation & State
Procedural Abstraction
Iteration
Recursion
Wishful Thinking
Order of Growth
Fundamental concepts of computer programming

18. Textbook : SICP
FREE!!
Available online at

19. Supplementary Text ALSO FREE!!
Available online at

20. Supplementary Reference 2
ALSO FREE!!
Available online at

21. Scheme Interpreter We will be using DrScheme It’s FREE!!!
Download from:

22. Assessment Overview Tutorial participation: 10% Problem sets: 30%
Midterm exam: 15%
Practical exam: 15%
Final exam: %

23. Cool Stuff Learn to make Stereograms Learn about RSA encryption
Build a Lego Robot
Write a text-based Adventure Game
Regular Programming Contests to keep students challenged

24. CS1101S Robot Contest

25. CS1101S Robot Contest
See more at CS1101S Facebook Group

26. CS1101S vs. CS1101 Progression: CS1101S  CS1102S CS1101  CS1102
Two-semester sequence
Discouraged from crossing over
CS1101S  CS1102, CS1101  CS1102S
Similarities
S and non-S versions both teach basic programming principles

27. CS1101S/02S vs. CS1101/02 Differences
CS1101S/02S cover more advanced topics
More challenging
CS1102S covers Java + more
Good introduction to many computer science topics

28. Which to take? Take CS1101S/02S if you want to be challenged.
If you have programmed before
No real advantage
In fact, can be a disadvantage!
If you have never programmed before
Great! You are not at a disadvantage.
Keep an open mind.
If CS is not your first choice course, CS1101S is probably NOT a good choice.

29. Java vs Scheme: What’s the Tradeoff?
sophisticated, mature
can be used for commercial applications
but has many underlying concepts that a beginner may find hard to understand
Scheme:
simple, elegant
easy to learn (hard to master)
designed to illustrate the concepts
BUT you will eventually learn Java anyway….
Mainly a question of personal choice (taste?)

30. What your seniors say….

31. What your seniors say…. [What doesn’t kill you makes you strong]
I think Scheme really does bring about concepts easily. Java's messy, so messy for an amateur programmer.
(on Problem Sets) They are all very difficult, but some are killers.
I learnt a tiny bit of java before I attended this class and I was totally lost. Teaching introduction to programming in Scheme is a quite smart idea. I feel much better when I came back to Java at the end of this class.
[What doesn’t kill you makes you strong]

32. What your seniors say….
I was warned by my seniors not to take scheme because they said it was very tough .... now when I’ve done this module , I agree that it is tough.. but it is worth the effort ..scheme makes u smarter !!! :)
Do you agree that Scheme is easier than Java? 32% NO; 68% YES!
The pace might be fast but if a person is able to handle it I think they would definitely benefit from it and enjoy it more than CS1101XYZ

33. More comments here ….
teaching/cs1101s06-midterm.htm
teaching/cs1101s06-final.htm
teaching/cs1101s07-midterm.htm
teaching/cs1101s08-midterm.htm
Just Google “cs1101s survey”!!!

34. 10 Reasons NOT to take CS1101S If you hate Math
If you don’t like challenges
If you cannot manage self-studying and need to be spoonfed
If you just want to get a free A
If you are not interested in learning more

35. 10 Reasons NOT to take CS1101S
If you don’t like personalised attention
If you don’t wish to meet like-minded peers
If you don’t care about applying your knowledge
If you don’t take shocks well/if you fear evilness
If you don’t like shuai prof :P

36. QUESTIONS

37. THANK YOU