Course Overview and Goals

This course is about principles, concepts, and ideas that underly programming languages. But what does this statement mean?

As a student of computer science, it is completely reasonable to think and ask, ``Why bother? I'm proficient and like programming in Ruby. Isn't that enough? Isn't language choice just a matter of taste? If not, should I be using another language?''

Certainly, there are social factors and an aspect of personal preference that affect the programming languages that we use. But there is also a body of principles and mathematical theories that allow us to discuss and think about languages in a rigorous manner. We study these underpinnings because a language affects the way one approaches problems working in that language and affects the way one implements that language. At the end of this course, we hope that you will have grown in the following ways:

We will dissect programming languages by constructing interpreters. The semester project is to construct an interpreter for JavaScript (incrementally). We will see that interpreters are the basis for realizing computation, and we will study the programming language theory that enable us to reason carefully about a language's design and implementation. Our approach will be gradual in that we will initially consider a small subset of JavaScript and then slowly grow the aspects of the language that we consider.

Incoming students often expect this course to be what I will call a trip to the Zoo of Programming Languages. While it is certainly interesting to go to the zoo, we seek a more informative and sciencific study of the underlying principles. A more apt analogy is an anatomy course where we will study the "guts" and inner-workings of programming languages. After this course, such an anatomological study will enable us to compare and constrast programming languages in a substantive manner and address the learning goals outlined above.

The course covers many aspects of using, understanding, and reasoning about programming languages (e.g., syntax, scoping, induction, data types, and typing). We will build up a set of mathematical tools for careful discourse. A significant part is devoted to abstraction, that is, how languages help programming in the large (e.g., subtyping polymorphism, parametric polymorphism, modules, and objects).

This course prepares you for introductory courses on both programming language implementation (e.g., CSCI 4555) and programming language semantics (e.g., CSCI 5535).


The official prerequisites for this course are CSCI 2270 (Computer Science 2: Data Structures) and one of CSCI 2400 (Computer Systems) or ECEN 2120 (Computers as Components). Familiarity with discrete mathematics from CSCI 2824 Discrete Structures is also important.

The course prerequisites are not necessarily absolute. However, it is strongly advised that you have already completed Data Structures, and Computer Systems and Discrete Structures are at the minimum taken concurrently. If you have not already taken these courses or if you have any concerns, please talk with the instructor. Proficiency in programming is absolutely expected, though there is no specific language required. This means that you should be able to pick up a new programming language with relative ease. You will be expected to learn new programming languages with guidance but relatively independently in this course.


You will be responsible for the following:

Grading. Your overall grade will be determined using the ratio for lab assignments, quizzes, teaching project, the midterm exam, the final exam, and class participation shown above. There is no predetermined curve (i.e., I hope everyone gets an A based on the level of mastery demonstrated). Cutoffs will be announced after the midterm exam to give you an idea where you stand.

Regrades. Any request for reconsideration of any grading on coursework must be submitted within one week of when it is returned. Any coursework submitted for reconsideration may be regraded in its entirety, which could result in a lower score if warranted. To request a regrade, please go to the instructor's office hours with your coursework and an explanation of what you believe the grading error to be.

Make-Up Exam Policy. There will be no special or make-up examinations for any student (except in the case of emergency or the stated special accommodations).

Late Assignment Policy. This course is project-based, which means the learning is driven primarily by the lab assignments. To encourage iteration until mastery, you may resubmit until the second to last week of the semester (December 7) for a maximum of 85%. You may request one regrade per assignment up until the December 7 deadline. However, you may discuss your solutions with the instructors in office hours as much as you like before requesting your regrade.

Extra Credit and Participation. Extra credit opportunities may be offered during the course semester. Extra credit is recorded separately from normal grades and are only considered after final grades have been calculated. If your final grade is just below a grade cutoff, extra credit may bump you up to the next grade.

Pair Programming. You are encouraged to work on lab assignments in pairs, enabling pair programming. Lab assignments are the main opportunity to learn material in this course and thus they count for a relatively small portion of your final grade. It is strongly advised that you work on all the problems in a lab assignment together so that you understand all of the material and are prepared for the exam. Everyone will submit assignments, and you must cite your partner explicitly. You may switch partners between assignments, and you are responsible for all assignments individually (e.g., if your partner drops the course midway though an assignment, you still need to submit on time).

Workload. CSCI 3155 is a 4-credit course.


Both your ideas and also the clarity with which they are expressed matter—both in your English prose and your code!

We will consider the following criteria in our grading:

Textbook and Resources

Textbook. The primary textbook for the course is Essentials of Programming Languages, 3rd edition by Daniel P. Friedman and Mitchell Wand. We will take liberty to deviate the textbook where appropriate as we will use a different implementation language (Scala instead of Scheme). Supplemental course notes will also be distributed as appropriate. This book is available as an e-book to all University students.

We also strongly recommend that you get access to Programming in Scala, 2nd edition by Martin Odersky, Lex Spoon, and Bill Venners. This book is an extended tutorial for learning Scala by those directly involved in the language's development.

Supplemental Books. The following books are not required. We may make reference to them, and you may find them useful as alternative presentations of similar material. Both of these books (along with Essentials of Programming Languages) are also on reserve in the Engineering Library.





Moodle. We will use Moodle for grades and feedback. If you do not already have an account, please create one and join the course moodle. The enrollment key is in the welcome e-mail.

Piazza. We will be using Piazza for online, outside-of-class discussion. Rather than emailing questions to the teaching staff, questions should be posted on Piazza. I encourage you to make class-wide posts whenever possible, but there is an option to send an instructor-private message. You also have the option of posting anonymously.

PL-Detective. The PL-Detective is a tool developed by Prof. Amer Diwan et al. The PL-Detective aims to make learning programming language concepts fun, while attempting to address many of the goals enumerated above. We will use the PL-Detective for assignments and classroom demonstrations.

Computing. For a Linux environment, the following are some resources:

Collaboration Policy

You are welcome and encouraged to work together in learning the material. If you worked with someone on an assignment, or if your submission includes quotes from a book, a paper, or a web site, you should thank the source. Bottom line, feel free to use resources that are available to you as long as the use is reasonable and you cite them in your submission. However, note that copying answers directly or indirectly from solution manuals, web pages, or your peers is certainly unreasonable. If you have any doubts in this regard, please ask the course staff.

We will go by the Honor Code set forth by the University:

All students of the University of Colorado at Boulder are responsible for knowing and adhering to the academic integrity policy of this institution. Violations of this policy may include: cheating, plagiarism, aid of academic dishonesty, fabrication, lying, bribery, and threatening behavior. All incidents of academic misconduct shall be reported to the Honor Code Council and those students who are found to be in violation of the academic integrity policy will be subject to both academic sanctions from the faculty member involved and non-academic sanctions given by the Honor Code Council (including but not limited to university probation, suspension, or expulsion).

Please refer to to view the specific guidelines. If you have any questions related to this policy, please contact the Honor Code Council at

Classroom Behavior

We trust and expect everyone to behave in a civil and courteous manner.

In class, the course staff promises their undivided attention and reciprocally expects the same from you. In today's world, this promise requires turning off transmitting devices, such as cell phones and wi-fi on notebook computers. Notebook computers should be used only for purposes directly relevant to the class discussion (e.g., taking notes). Please notify the course staff if you encounter behavior that distracts from your learning.

Discrimination and Sexual Harassment

We will go by the policies set forth by the University:

The University of Colorado at Boulder policy on Discrimination and Harassment, the University of Colorado policy on Sexual Harassment and the University of Colorado policy on Amorous Relationships apply to all students, staff and faculty. Any student, staff or faculty member who believes s/he has been the subject of sexual harassment or discrimination or harassment based upon race, color, national origin, sex, age, disability, creed, religion, sexual orientation, or veteran status should contact the Office of Discrimination and Harassment (ODH) at 303-492-2127 or the Office of Judicial Affairs at 303-492-5550. Information about the ODH, the above referenced policies and the campus resources available to assist individuals regarding discrimination or harassment can be obtained at

Special Accommodations

We will make every effort to make special accommodations that are reasonable and fair to all students. Please note that we will accept requests for adjustments during the first four weeks of class.


We will go by the disability guidelines set forth by the University:

If you qualify for accommodations because of a disability, please submit to the course staff a letter from Disability Services within the first four weeks of class so that your needs can be reasonably addressed. Disability Services determines accommodations based on documented disabilities (303-492-8671, Willard 322).

If you have a temporary medical condition or injury, see these guidelines.

Disability Services' letters for students with disabilities indicate legally mandated reasonable accommodations.

Religious Observances

We will go by the policy for religious observances set forth by the University:

Campus policy regarding religious observances requires that faculty make every effort to deal reasonably and fairly with all students who, because of religious obligations, have conflicts with scheduled exams, assignments or required attendance. In this class, we will try to accommodate religious conflicts in a reasonable manner. Please check the exam dates and submit all requests for adjustments within the first four weeks of class.

See for further details on the policy.


This course has benefited from the organization and experience from prior versions of this class taught by Amer Diwan, Michael Main, William Waite, Martin Hirzel, and Clayton Lewis.