91.301 Organization of Programming Languages, Spring 2014
Prof. Fred Martin, click for fred's email
TA: Swathi Kurunji, firstname.lastname@example.org. Office hours: 2 to 4 pm on Tuesdays.
Mon/Wed/Fri, 1p 1:50p, Olsen 402
We will be using the following book:
Structure and Interpretation of Computer Programs (2nd edition, 1996, ISBN 0070004846)
Hal Abelson and Jerry Sussman
The Abelson/Sussman book is available online (for free) here. If you like holding a book in your hands, used hard copies are available between $30 and $40. Make sure to get the 2nd edition, published in 1996. Here are links: bigwords, alibris, amazon, bookfinder
Hal Abelson (in introduction to SICP):
Fred Martin (email communication):
Franklyn Turbak (computer scientist at Wellesley College; email communication, edited slightly):
Basically all departments that award bachelor's degrees in Computer Science have a course like OPL. Such a class is also required by CSAB, the professional organization that accredits CS degrees. So, everyone's got onewhy?
In my opinion, this course exists to give you a different way of thinking about computing. A way that is really quite apart from the professional programming languages like C, C++, and Java, all of which are based on an edit/compile/debug/deploy model of computation.
There are basically two variants of the OPL-type course at CS departments. One variant is a survey of the ideas in many languages that have been created and implemented. The other variant is a deep-dive into a language favored by language researchers, often Scheme or CAML. Both of these languages are meta-languagesthey are languages for making languages.
At UMass Lowell, we take the 2nd approach (deep dive) in our undergrad course, and the survey approach in our grad class. For many years here, 91.301 has been a close implementation of the famous 6.001 course at MIT, Structure and Interpretation of Computer Programs. This course was created in the 1970s and has been hugely influential.
Now, it so happens that MIT has just implemented a major overhaul of their undergrad EECS curriculum, and as of Fall 2008, the 6.001 course is no longer being offered. Given that, why are we still teaching it, you might ask?
Isnt Scheme a Dead Language? (aka, Why do I have to take this class?)
Scheme isn't exactly dead. There is a committed community involved in on-going development of the version of Scheme we'll be using (Racket). Scheme itself is a streamlined, pedagogically pure version of Lisp; Lisp is an expanded version of the language, with lots of libraries useful in real-world applications. While not hugely popular, there are still significant real-world systems being built in Lisp. The Orbitz flight reservation system is a leading example.
More importantly, the ideas behind Schemee.g., functional programmingare valuable, even if you're not coding in Scheme.
- Jane St. Capital, a Wall Street trading company, does a lot of programming in OCaml, and object-oriented functional programming language, and explicitly recruits Scheme programmers. (See their research paper at http://portal.acm.org/citation.cfm?id=1394798).
- It is now clear that processors aren't going to be getting faster at the rate they have been over the last 20 years, and that multi-core systems and their associated programming will be increasingly important in order to continue the performance gains we expect. Functional programming is much easier to parallelize than traditional imperative styles, and many believe that expertise in thinking in functional ways is becoming more and more important. See the recent Dr. Dobbs article, It's Time to Get Good at Functional Programming.
- Many languages, including C++, now incorporate ideas that originated in Lisp/Scheme, including closures and anonymous functions.
- Aside from the particular concepts in Scheme or Lisp, they represent a fundamentally different approach to building languages than the dominant method, which is based on compilers and binary executables. Scheme and Lisp are implemented as interpreters, and interpreters allow a much more iterative and interactive style of code development. Python is the presently the most popular language that is based on the interpreter approach. Also, interpreters are often built into domain-specific applications as powerful, accessible scripting environments within those applications; Tcl and Lua are other languages often built into systems as interpreters. AutoCAD and GIMP are two well-known systems that include Lisp or Scheme interpreters.
What Is The Big Idea Then?
There are actually several big ideas that we will bring out in OPL:
- Program-as-data. In typical programming languages, there is a sharp distinction between what is code and what is data. Data structures are allocated explicitly, and code is written to manipulate them. The two things are of a different nature. (Of course, bits are bits, but you're not going to be placing executable code into an array unless you're implementing a buffer overrun attack.)
- Functions as first-class objects. In Scheme, procedures (also known as functions) can accept procedures as inputs (arguments). But they also can easily create procedures as outputs (return values). This leads to a style of programming known as functional programming, in which functions are composed and applied to lists of data to produce results, instead of the more prevalent approach of sequentially manipulating data structures.
- Data abstraction. This was one of the really big contributions of SICPthe idea of abstracting data structures from the interfaces for manipulating them. It then becomes possible to re-implement an underlying data structure without changing the code that uses it. For example, if there is a
concatenateoperation that appends one string to another, code that uses
concatenatedoesn't need to change even if the underlying representation of a string changes.
- The environment and persistence. In typical programming environments, data and objects are created anew each time the program launches. If you need to return to a previous execution state, then you read in data (e.g., from files on the disk or off the net) and reconstitute the data structures that hold that data. Object-oriented languages typically provide some way to serialize objectsconverting them into a flat-file format (e.g., XML) for saving and loading across execution runs.
- Interpretation and the Listener. Scheme was historically an interpreted language, and provided a Listener console for interactively constructing expressions and evaluating them. (At one time, the fact that it was interpreted was considered a significant performance liability, but compiled versions of Scheme and Lisp now exist, removing this as a concern.)
mainfunctions simply for the purpose of exercising your routineswhy can't you just talk to them directly? Similarly, the environment is a powerful constructyou build up a library of objects that are part of your project, and once created, they are part of your software system.
Course Structure and Grading
The class will have regular weekly assignments, which will be graded and returned. Cumulatively these assignments are worth 25% of your overall grade. Assignments will be accepted up to 1 week late with a 50% reduction in that assignment's value. If you fall behind on your homework, it is much better to cut your losses and work on the current assignment, instead of running behind trying to catch up.
There will be two in-class quizzes during the semester. Each is worth 10% of your overall grade.
There will be a cumulative final, worth 20% of your overall grade.
Classroom participation is worth 10% of your overall grade. In practice, if your other grades put you on a marking boundary, this will push it one way or the other.
You may notice that this leaves 25% remaining. Based on last semester's success, I am continuing with a course final project, which will be conducted in the last three weeks of the semester. We will exploratory research and discussions before then, though, so you can start preparing for it.
In the final project, you will apply the ideas developed in the class in an original software implementation. You may thus connect the ideas of the class with your own interestsmusic, robotics, art, databases, the web, networking, gaming, etc. The learning goal of the project is to have you find some real-world relevance of the ideas in the class.
25% Weekly homeworks
20% Two quizzes
10% Classroom participation
We will use the “Bottlenose” autograder system for assignment submission and grading. Click on the Assignments tab at the top of the web page to see the Assignments.
You already have been made an account in Bottlenose, using your
@student.uml.edu email address. You should have a link in your inbox with a key to log in.
If you lose the email, you can just enter your email address at the Bottlenose main screen and it will email it to you again.
We'll go over how to use Bottlenose in class.
Discussion Group / E-Mail List
We will use Google Groups for class conversation and announcements. Please join this group.
There are two ways to sign up:
- (better) Log in to your Google account, go to https://groups.google.com/forum/#!forum/91301-s14, and request to join, or
- (easy but then no web access) Enter your preferred email in the box below.
|Subscribe to 91301-s14|
If you do the Google web method, I'd advise setting your preferences to immediate, individual delivery of messagesclick the Edit my membership tab.
If you do the email method, and you provide an address that's not linked to your Google account, I'll choose those delivery options for you, and then if you don't like it you'll have to ask me to change it, and we'll both be annoyed, so don't do that.
In either case you can send email to the list with mailto:email@example.com.
If you sign up on the web, you can browse conversations at the group link (see top of this page).
Lecture blog and lecture capture
I will strive to maintain a daily blog of highlights of what happened in class each class meeting. These notes will be recorded in the Lecture Blog page.
In-class activity will be recorded using the University's Echo360 lecture capture system. This material is intended for your use if you must miss class, or if you want to go over again something that was presented/discussed in class.
A link to the Echo360 recordings is at the top of the Lecture Blog page.
Echo360 makes a high quality recording of the classroom's data projector and the instructor's voice.
It also produces a low-resolution recording of the front of the room (i.e., me walking around writing stuff on the white board), and a low-volume capture of student remarks (depending how close to the microphone you're sitting, and how loud you are).
If you arrive at class after 1p, and walk across the front of the room, you'll be captured by the low-res overview cam.
If you're a talker and you're at a decent volume and near a mic, people will be able to hear you on the recording. (They won't see you sitting in your chairmaybe the back of your head if you're at the front of the room.)
If it bothers you that your voice will be captured, and you want to feel comfortable speaking up, please let our TA know and the TA will anonymously refer your concerns to me. We'll set up the captures in a more private way.
Individual work. Most assignments must be completed individually. You are welcome to discuss ideas in the class with your peers. You may not look at each others' code, nor allow others to look at your code. If you need to post code on our own course forum for help, or a public forum, do not post more than three lines.
When turning in an individual assignment, you attest that, beyond any starter code I have provided or has been provided in standard API and reference documentation, you are the sole author the code that it includes.
Pair programming. A few specific assignments may allow pair programming. There will be highly structured rules for these (which are intended to make sure both partners have a substantial learning experience).
This will be discussed later in class, and this document will be updated at that time.
Academic integrity. Please be familiar with the university's policy on academic integrity.
Much of this course design is based on work done by UML Prof. Holly Yanco.