### Course Description What does it mean for a C++ program to be "undefined"? What is the difference between "proc" and "lambda" in Ruby? What is the difference between "function" in Javascript and "lambda" in Python? What does "yield" do in the various programming languages that support it? What is the difference between a "variable", a "pointer" and a "reference"? What's the difference between a Javascript "prototype", a Java "class", and a Rust "trait"? If I wanted to automatically translate python to javascript, and in a way that preserves the original program's meaning, (1) how would I do it, and (2) how would I know I did it correctly? This course will explore topics in programming language design, implementation and analysis. We will examine existing programming language designs, as well as give a rigorous mathematical account for core subsets of programming language features. Finally, we will use this mathematical account of programming language semantics as a foundation for tools which analyze programs to (a) find bugs in programs, (b) verify correctness and security properties of programs, and (c) automatically construct programs which adhere to a specification. This course is structured around *language interpreters* as an avenue for exploring language features and mathematical properties of programs. We will not study any single mainstream programming language, rather we will focus on smaller toy languages in order to focus on the essence of language features in isolation. After studying language features through interpreters, we will relate these features back to mainstream programming languages and discuss their designs. Students are expected to implement concepts discussed in the course in the Haskell programming language, and manipulate mathematical definitions of programming language semantics on paper. Students will be evaluated through weekly programming assignments, a midterm exam and a final project. There will be no final exam. **Prerequisites:** CS 124 (Data Structures and Algorithms) and CS 125 (Computability and Complexity) ### Administration **Lecture:** Tuesdays and Thursdays, 1:15–2:30pm, Aiken Center 110 **Instructor:** [David Darais](http://david.darais.com) **Office Hours:** - Tuesdays, 4:00–5:00pm, Votey 319 - Wednesdays, 4:00–5:00pm, Votey 319 **TA:** Lindsey Stuntz **Office Hours:** - Tuesdays, 10:00-12:00pm, CS Conference Room **Course Piazza:** [CS 225: Programming Languages][Piazza] [Piazza]: https://piazza.com/class#spring2019/cs225 *Course announcements and discussion will take place on Piazza exclusively. Questions sent to the instructor or TAs via email will receive the following reply: “Please post this question to Piazza.” The instructor and TAs are not required to respond to Piazza questions after 5pm, or any earlier than 24 hours after the question is posted.* ### Textbook We will use Shriram Krishnamurthi's [Programming Languages: Application and Interpretation][PLAI]. The book is freely available online. Although the book uses Racket for programming examples and exercises, we will be using Haskell. Aside from this change in implementation language, we will follow the book quite closely. We will deviate from the book to explore a broad range of advanced topics towards the end of the course. [PLAI]: http://cs.brown.edu/courses/cs173/2012/book/ ### Software Tools Throughout the course we will use the [Haskell] programming language. See [Haskell Setup][HaskellSetup] for instructions on setting up Haskell. We will use Haskell GHC version 8.6.3 for this course, along with the [Stack] tool for managing Haskell compiler and package installations. You may find [Hoogle] useful for looking up documentation of Haskell operators and functions. [Haskell]: https://haskell-lang.org [HaskellSetup]: haskell-setup.html [Stack]: https://haskellstack.org [Hoogle]: https://www.haskell.org/hoogle/ ### Policies **Grades:** Your grade for the course will be calculated as follows: 60% Assignments, 20% midterm and 20% final project. Grades for assignments will be calculated based on tests passed in our grading scripts. *I will drop your lowest assignment grade.* This means that out of the 9 assignments, your best 8 will be used to calculated 60% of your grade, so each assignment is worth 7.5% of your total grade. Letter grades are calculated in the [usual way][LetterGrades]. A+ will only be given to students who achieve 97–100% *and* an outstanding final project. [LetterGrades]: letter-grades.html I will grade assignments within one week and post snapshots of your grade after each assignment. *I will not create new extra credit opportunities for students who are unhappy with their grades late in the semester.* You will have all of the information you need to achieve your desired grade by the end of the course: your grade at any given point in the course, and the formula I will use to calculate final grades at the end of the course. Students concerned about their grade should schedule a meeting with me promptly after the midterm. **Extra Credit:** During the semester there will be ~7 guest lectures from visiting faculty. *I will give 0.5% extra credit towards your final grade for each of these lectures that you attend.* To receive extra credit, you must bring a notepad to the lecture, take notes in person during the lecture, and then turn your notes in to the instructor or TA personally at the end of the talk. If you attend all lectures you will receive a ~3.5% bump to your final grade. - Guest Lecture 1: Tuesday, February 12, 12–1pm (Systems Security) - Guest Lecture 2: Thursday, February 14, 12–1pm (CS Theory) - Guest Lecture 3: Tuesday, February 19, 12–1pm (Systems Security) - Guest Lecture 4: Friday, February 22, 12–1pm (Systems Security) - Guest Lecture 5: Tuesday, February 26, 1–2pm (Systems Security) (CLASS CANCELED) - Guest Lecture 6: ??? (CS Theory) - Guest Lecture 7: ??? (CS Theory) - Guest Lecture 8: Monday, March 04, 12–1pm (Systems Security) **Assignments:** There will be 9 weekly assignments. Each assignment is released on a Thursday after class and due the following Thursday *before class*. Your lowest assignment grade will be dropped when calculating final grades. **Late Work:** Each assignment will be released after class on a Thursday and due before class one week later. *Late work will not be accepted.* The purpose of my policy to drop your lowest homework grade (see above) is to accommodate situations that interfere with turning in assignments on time: e.g., illness, travel, extracurricular activities, or other coursework. Please use this “free” assignment carefully, and only for situations that are truly outside your control. **Collaboration and Copying:** Collaboration with peers on the high-level ideas and approach on assignments is encouraged. *Copying someone else's work is not allowed.* Any collaboration, even at a high level, must be declared when you submit your assignment. Every assignment must include a collaboration statement. E.g., “I discussed high-level strategies for solving problems 2 and 5 with Alex.” Obtaining high-level information on the internet is allowed and encouraged if it helps you learn the material. However, I strongly discourage googling for answers to homework problems. *Copying code from the internet and submitting copied content for assignments is not allowed.* Students caught copying work from peers or submitting copied code from the internet will be eligible for immediate failure of the course and disciplinary action by the University. All academic integrity misconduct will be treated according to [UVM's Code of Academic Integrity][UVM-CAI]. [UVM-CAI]: https://www.uvm.edu/policies/student/acadintegrity.pdf **Small Group Assignments:** For homeworks 5–9 you will be allowed to work in groups of size 1–2 (independently or in pairs). You may submit a single solution to the assignment for 2-person groups. **Midterm:** The midterm will be closed note, closed book and closed laptop. **Final Group Project:** For the final project, you will be allowed to work in groups of size 1–2, however I will expect a larger amount of work to be completed for groups of 2. For the final project you will do the following, all of which will be graded: - Submit a project proposal as part of HW 9 - Submit a project checkpoint each week for two weeks - Present your project during the last week of classes - Submit your final project on the last Friday of classes **Special Topics Lectures:** Possible special topics include: - Effects, via Monads - Logic Programming, via MiniKanren - Software Verification, via LiquidHaskell and/or Dependent Types - Static Analysis, via Galois Connections - Memory Safe Languages, via Rust - Security and Privacy, via Duet ### Schedule Date | Topic | Homework ------------|------------------------------------------------------------------------------------|------------------------------------- Tue, Jan 15 | Welcome [[LN01]] | Thu, Jan 17 | Technical Intro ⅋ Haskell [[LN02]] | HW 1 Release [[HW01]] [[SL01]] Tue, Jan 22 | Syntax ⅋ Interpretation [[LN03]] [[LC03]] | Thu, Jan 24 | Desugaring ⅋ Partiality [[LN04]] [[LC04]] | HW 1 Due ⌁ HW 2 Release [[HW02]] [[SL02]] Tue, Jan 29 | Lists, Trees, Sets ⅋ Variables [[LN05]] [[LC05]] | Thu, Jan 31 | Binding and Scope [[LN06]] [[LC06]] | HW 2 Due ⌁ HW 3 Release [[HW03]] [[SL03]] Tue, Feb 05 | Substitution [[LN07]] | Thu, Feb 07 | Functions ⅋ Environments [[LN08]] [[LC08]] | HW 3 Due ⌁ HW 4 Release [[HW04]] [[SL04]] Tue, Feb 12 | Functions II [[LN09]] | Thu, Feb 14 | Haskell Review | HW 4 Due ⌁ HW 5 Release [[HW05]] [[SL05]] Tue, Feb 19 | Higher Order Haskell [[LN11]] [[LC11]] | Thu, Feb 21 | Mutation [[LN12]] | HW 5 Due ⌁ HW 6 Release [[HW06]] [[SL06]] Tue, Feb 26 | *NO CLASS* (Guest Lecture) | Thu, Feb 28 | **REVIEW FOR MIDTERM** [[MidtermPractice]] | HW 6 Due Tue, Mar 05 | *NO CLASS: Town Meeting Day* | Thu, Mar 07 | **MIDTERM** | Tue, Mar 12 | *NO CLASS: Spring Break* | Thu, Mar 14 | *NO CLASS: Spring Break* | Tue, Mar 19 | Objects [[LN13]] | Thu, Mar 21 | Self Reference ⅋ Core OO [[LN14]] | HW 7 Release [[HW07]] Tue, Mar 26 | Representation | Thu, Mar 28 | Macros | HW 7 Due ⌁ HW 8 Release Tue, Apr 02 | Continuations | Thu, Apr 04 | Types | HW 8 Due ⌁ HW 9 Release Tue, Apr 09 | Contracts | Thu, Apr 11 | Evaluation Strategies | HW 9 Due ⌁ Start Project Tue, Apr 16 | Special Topic: (TBD) | Thu, Apr 18 | Special Topic: (TBD) | Project Checkpoint 1 Due Tue, Apr 23 | Special Topic: (TBD) | Thu, Apr 25 | Special Topic: (TBD) | Project Checkpoint 2 Due Tue, Apr 30 | Project Presentations II | Thu, May 02 | Project Presentations II | Fri, May 03 | *NO CLASS* | Project Due (at 11:59pm) [LN01]: ln/ln01.html [LN02]: ln/ln02.html [LN03]: ln/ln03.html [LN04]: ln/ln04.html [LN05]: ln/ln05.html [LN06]: ln/ln06.html [LN07]: ln/ln07.html [LN08]: ln/ln08.html [LN09]: ln/ln09.html [LN10]: ln/ln10.html [LN11]: ln/ln11.html [LN12]: ln/ln12.html [LN13]: ln/ln13.html [LN14]: ln/ln14.html [LN15]: ln/ln15.html [LN16]: ln/ln16.html [LN17]: ln/ln17.html [LN18]: ln/ln18.html [LN19]: ln/ln19.html [LN20]: ln/ln20.html [LN21]: ln/ln21.html [LN22]: ln/ln22.html [LN23]: ln/ln23.html [LN24]: ln/ln24.html [LN25]: ln/ln25.html [LN26]: ln/ln26.html [LN27]: ln/ln27.html [LN28]: ln/ln28.html [LN29]: ln/ln29.html [LC01]: lc/Lc01.hs [LC02]: lc/Lc02.hs [LC03]: lc/Lc03.hs [LC04]: lc/Lc04.hs [LC05]: lc/Lc05.hs [LC06]: lc/Lc06.hs [LC07]: lc/Lc07.hs [LC08]: lc/Lc08.hs [LC09]: lc/Lc09.hs [LC10]: lc/Lc10.hs [LC11]: lc/Lc11.hs [LC12]: lc/Lc12.hs [LC13]: lc/Lc13.hs [LC14]: lc/Lc14.hs [LC15]: lc/Lc15.hs [LC16]: lc/Lc16.hs [LC17]: lc/Lc17.hs [LC18]: lc/Lc18.hs [LC19]: lc/Lc19.hs [LC20]: lc/Lc20.hs [LC21]: lc/Lc21.hs [LC22]: lc/Lc22.hs [LC23]: lc/Lc23.hs [LC24]: lc/Lc24.hs [LC25]: lc/Lc25.hs [LC26]: lc/Lc26.hs [LC27]: lc/Lc27.hs [LC28]: lc/Lc28.hs [LC29]: lc/Lc29.hs [HW01]: hw/Hw01.hs [HW02]: hw/Hw02.hs [HW03]: hw/Hw03.hs [HW04]: hw/Hw04.hs [HW05]: hw/Hw05.hs [HW06]: hw/Hw06.hs [HW07]: hw/Hw07.hs [HW08]: hw/Hw08.hs [HW09]: hw/Hw09.hs [SL01]: sl/Sl01.hs [SL02]: sl/Sl02.hs [SL03]: sl/Sl03.hs [SL04]: sl/Sl04.hs [SL05]: sl/Sl05.hs [SL06]: sl/Sl06.hs [SL07]: sl/Sl07.hs [SL08]: sl/Sl08.hs [SL09]: sl/Sl09.hs [MidtermPractice]: midterm/practice.pdf