Textbooks

• Crafting Interpreters by Robert Nystrom.
• Programming in Scala by Odersky, Spoon, Venners, and Sommers, 5th edition, published by Artima Press.

In the first half of the course, we will look at a toy implementation of a programming language, called Lox. We will go through parts I and II of Crafting Interpreters (the java interpreter). The textbook is free in its HTML form, which is excellent. You can also buy a PDF or hard copy.

The first half of the course will also introduce Scala, which is an industrial-strength language. We will look at functional programming in Lox and Scala, with an emphasis on understanding higher-order functions and closures.

In the second half of the course, we will look at additional language features in Lox, Scala, Javascript, and other languages. In particular, we will look at how Lox and Scala integrate object-oriented features. The Scala text we use is excellent -- it describes the language from the point of view of a programming language theorist.

Software

• Java. I recommend version 21, which has long term support (LTS), but later versions are fine.
• VSCode. You don't technically need this, but you do need some editor. And VSCode does everything we need. You need to install some extensions:
  • Extension Pack for Java
  • Scala (Metals)
  • JavaScript and TypeScript Nightly (optional)
• Homebrew. If you are on a mac, you will need Homebrew to install Maven and Scala. If you are Windows you can skip this step.
  • Be sure to do the "Next Steps" printed on the terminal after executing the brew install script.
  • Here is a step-by-step guide.
• Scala. We will use Scala as an example language. To install it, just follow the instructions at the top of the download page.
  • For now, we will simply run the Scala interpreter from the command line.
  • After installing, (re)start a terminal window and type scala. You should get a message with the Scala version, followed by the prompt scala>. At this prompt you can type any Scala expression, such as 1 + 5. After you press the return/enter key, Scala will read the expression, evaluate it, and print the result. The is a Read-Eval-Print loop, or REPL.
  • Later in the quarter we will be using a Scala tool called sbt. If sbt says server failed to start and Could not create lock then there is another instance of sbt running. Exit all your programs and try to delete the target directory using the finder/windows explorer. If that does not work, restart your computer and try again. Once you can delete the target directory, then you can start VSCode and sbt again.
  • VSCode understands build.sbt files, but seems to be a bit slow about picking up tests. If you want to run sbt tests using VSCode buttons, then it seems to be necessary to open a single test file in the VSCode editor. After doing this, VSCode seems to recognize all of the test files properly.
• Maven. We will use Maven to build, test, and run a toy language interpreter, written in java. The toy language is called Lox.
  • On a mac, type brew install maven
  • On windows, you install the zipfile from the maven website and then add the maven bin directory to your path. Here is a step-by-step guide.
  • To compile the Lox interpreter, download the source code from the course webpage and unzip it; in the terminal, change directory into the unzipped folder that contains the file pom.xml. In that folder, run mvn compile. If mvn compile says there is no POM in this directory then you are starting mvn in the wrong directory.
  • Run the tests using mvn test.
  • After compiling, you can run the Lox interpreter with java -cp target/classes com.craftinginterpreters.lox.Lox. You must be in the same directory where you successfully executed mvn compile.
  • I like running a combination command on my mac:

    mvn -q clean compile && java -cp target/classes com.craftinginterpreters.lox.Lox

    To run Lox on a file, I use:

    mvn -q clean compile && java -cp target/classes com.craftinginterpreters.lox.Lox x.lox

    Note: The option -q suppresses non-error output. On my system, this does not behave as I expect unless I add the clean command.

General Resources

Please report broken links to the instructor.

Online Editors/Compilers/Interpreters

• General read-eval-print-loop: repl.it (Note that BiswaScheme does not support rational literals)
• General compiler: godbolt.org