CS 201 - Spring 2025. 1/13/2025.

Welcome to CS 201!

Note: you can find this page by going to the syllabus in canvas and then clicking "home" and "lectures" and "0113.html".

Video of the Day

Another Opening, Another Show

Based on a play by Shakespeare, with music by a Yale graduate, this number captures the feeling of hope, promise, uncertainty, and even trepidation felt by many of us in this course. Welcome back!

Logical problem of the day: 854-917-6320

What unique property does this number possess?

https://pollev.com/slade You may also download the app to your phone. Use the "slade" poll id. Note: you do not need to register. We don't grade these submissions.

Lecture 1: Introductory Lecture.

Discussion of Course and Instructor: Stephen Slade

Biography. Hybrid: academia (theory) / industry (practice).
- Yale undergraduate. music major. (studied CS with Alan Perlis)
- Developed computer systems for presidential campaigns and the White House, introducing electronic mail to campaigns and the internet to the White House.
- Yale graduate student, M.S., Ph.D., computer science (artificial intelligence)
- Yale Computer Science Department: Assistant Chairman, Assistant Director of the Yale AI Project, Lecturer.
- Connected Yale to the Internet - also the White House. (stephen.slade@whitehouse.gov)
- NYU Stern School of Business, Department of Information Systems, Assistant Professor.
- Wrote three books (T/Scheme, LISP, decision making) - dedicated to Yale alumnae.
- Developed investment and risk technology systems for Wall Street. Sell side (Morgan Stanley), Buy side (INVESCO, Bank of America, Commonfund)
Syllabus,
I have office hours Wednesdays from 4-6 pm, on zoom, id 459 434 2854.
Note: You will be required to learn UNIX, as well as Racket/Scheme. Questions about UNIX will appear on all exams.
Other courses to consider
- CS 110. Python Programming for Humanities and Social Sciences.
  Sophie Park
  MW 11:35am - 12:50pm, plus sections.
  Introduction to computer science and Python programming with domain-specific applications. Students learn how to think algorithmically and solve problems efficiently. Topics include abstraction, algorithms, data structures, web development, and statistical tools. Students learn to apply computing techniques in the fields of social sciences & humanities by analyzing data. No previous programming experience is required. This course is intended for students of social sciences & humanities majors.
- CS 112. Introduction to Programming
  Instructor varies by section
  MW 11:35-12:50
  Development on the computer of programming skills, problem-solving methods, and selected applications.
- CS 123. YData: An Introduction to Data Science.
  Roy Lederman
  TTh 2:30pm - 3:45pm
  Computational, programming, and statistical skills are no longer optional in our increasingly data-driven world; these skills are essential for opening doors to manifold research and career opportunities. This course aims to dramatically enhance knowledge and capabilities in fundamental ideas and skills in data science, especially computational and programming skills along with inferential thinking. YData is an introduction to Data Science that emphasizes the development of these skills while providing opportunities for hands-on experience and practice. YData is accessible to students with little or no background in computing, programming, or statistics, but is also engaging for more technically oriented students through extensive use of examples and hands-on data analysis. Python 3, a popular and widely used computing language, is the language used in this course. The computing materials will be hosted on a special purpose web server.

Both CS 110 and CS 112 assume no prior programming experience. By contrast, CS 200 (in the fall) and CS 201 assume that this is not your first rodeo.

If you're thinking of taking CPSC 201, please do the following.

Complete this online Student Information form.
Get a course account for CPSC 201 on the Zoo. When you register for this class, your course account should be created within one hour or so of signing up.
Start the reading assignment: [Assignments].
Familiarize yourself with the Zoo computers with classmates or ULAs or on your own using the Zoo tutorial, Spring 2014 edition. We will discuss UNIX in class in the coming weeks and throughout the term. The compiled staff solutions to the problem sets are available for execution on the zoo. There is also an interactive UNIX tutorial available on the zoo.
(Optional.) Download and install DrRacket on your computer (Racket) and familiarize yourself with it (Choose language: "Use the language declared in the source", #lang racket. Then press the Run button to actually change the language.) If you don't want to install and run DrRacket on your machine, you may run it in person or remotely using your Zoo account.

Announcements

STEM Navigators Spring Kickoff and STEM Extracurricular Bazaar, Friday January 17th, 3 PM.

Come join STEM Navigators at our Spring Kickoff + STEM Extracurricular Bazaar on Friday, January 17th, from 3:00–4:00 PM at the Poorvu Center, Room 120A! Enjoy hot chocolate and cookies while meeting STEM Navigators mentors and members from 13 of Yale’s STEM organizations, representing fields ranging from healthcare to computer science and engineering. This is a fantastic opportunity to learn more about the STEM Navigators program, explore Yale’s STEM extracurriculars in a focused and intimate setting, and discover ways to engage with the STEM community. RSVP here, and check out the list of participating extracurriculars here. Everyone is welcome to attend, regardless of involvement in STEM Navigators!”

Ladies and Gentlemen, Start Your Engines!

Perlis epigram 19: A language that doesn't affect the way you think about programming is not worth knowing.

The language we'll use this term, Racket, is an offshoot of Scheme, which is an offshoot of LISP, which was designed as a higher-level language for writing artificial intelligence programs. We choose Racket because it is high-level, functional (as opposed to imperative), emphasizes recursion, and is unfamiliar to almost all students taking CPSC 201. It is definitely not widely used in industry. One goal is for you to learn new tools and paradigms for programming, to "affect the way you think about programming." It will be frustrating at times -- no assignment statements, no obvious analogs of for and while statements -- but it will expand your view of what programming can be.

We conclude with a gentle demonstration of Scheme (Racket) in action: 0113.rkt in which we do the following:

define a list comprising 10 digits
define a function, num-to-word, which takes a single digit, num, and returns the corresponding English word, e.g.,
(num-to-word 9) ==> "nine"
define a function, word-to-num, which is the inverse of num-to-word. Note that we define a sub-function within the function itself. The sub-function, find-index, is recursive.
We then try out the functions.
Here is a transcript of today's class.
Here is a jupyter notebook version of today's class.

The Big Picture

There is a standard scheme for giving a talk.

Tell the audience what you plan to tell them.
Tell them.
Tell them what you told them.

Today we are at step 1.

To some of you, the organization of topics in this course may seem hazy, like the shadows in Plato's cave. I want to assure you that, like in Blackadder, there is a cunning plan.

For years, academic computer scientists have debated the role of programming in introductory computer science courses. Many have argued that an introductory science course should expose the student to the great ideas of the discipline. Thus, an introductory biology course should cover topics such as evolution and molecular genetics, but not how to build a microscope. Accordingly, a computer science course should emphasize the major intellectual issues of computing, not how to write programs.
We do not agree with this position. First, programming is a major intellectual issue in computer science. Second, the comparison of programming to building a microscope misses the point. Writing programs in computer science is more like building a living organism in biology. If biology had advanced to a stage that permitted introductory students easily to construct amoebas and clams and roses and rabbits, there would be little debate over the intellectual content of such exercises. (Slade, The T Programming Language, 1987)

Here is the our framework.

Progamming and recursion. Learning racket allows us to have a grounded conversation.
Turing Machines. What are the limits to computing?
Boolean functions. What are the logical atomic elements of computation on which machines are built?
Gates and circuits. How do we wire up circuits?
TC 201 and computer architecture. How do we build a computer?
Strings and formal languages. How do we translate high level source code into machine language?
Computational complexity. Being computable is not sufficient if the algorithm is not efficient. How do we analyze algorithms?

For the next few months, we will execute step 2. On April 25th, I will execute step 3.

Note: there are three other rules for public speaking...

Racket.

Racket.html (jupyter)

Getting to know UNIX

UNIX Introduction

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