1 Install JDK and the Scala Toolchain🔗

The scala compiler scalac compiles Scala source code down to Java bytecode which is then interpreted by the Java Virtual Machine (JVM). Additionally, Scala Build Tool (sbt) is often used to manage and build the projects. Sbt will orchestrate the compilation and execution of Scala code by invoking the appropriate Scala and Java tools.

For this course, we are using the following versions,

• Java (OpenJDK 21)

• Scala 3.7.3

• sbt 1.11.7

Note that sbt manages the Scala and sbt version for each project individually (in its build file build.sbt). Once you have sbt installed, running sbt in the project directory will automatically download and use the correct Scala version. Note that Scala 2.x will not work for this course.

Using other versions of Java or sbt may work, but does not guarantee passing the tests when grading.

Installation instructions for these tools are as follows.

$ sudo apt-get install openjdk-21-jdk

$ brew install openjdk@21

$ javac -version
javac 21.0.9

$ sbt
[info] welcome to sbt 1.11.7 (Homebrew Java 21.0.9)
[info] loading project definition from <omitted>/proj1/project
[info] loading settings for project root from build.sbt...
[info] set current project to Project1 (in build file:<omitted>/proj1/)
[info] sbt server started at local: <omitted>
[info] started sbt server
sbt:Project1>

sbt:Project1> compile

sbt:Project1> console
Welcome to Scala 3.7.3 (21.0.9, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
scala>

2 Structure of Scala/sbt Project🔗

Although it would be possible to compile projects manually using the scalac command, scala projects use the sbt tool and have the following directory structure.

my-app
├── build.sbt
├── project/build.properties
└── src
    ├── main
    │   └── scala
    │       ├── util_package
    │       │   └── Lib.scala
    │       └── Main.scala
    └── test
        └── scala
            └── *Test.scala

The build.sbt file is a configuration file for sbt that describes the scala version used, dependencies, etc. Source files are usually found under src/main/scala. This directory denotes that the source files are Scala code. Test files are usually found under src/test/scala. Similarly to Java, package hierarchy is reflected in the directory structure.

3 C Compiler and Make🔗

$ sudo apt-get install build-essential gdb

If you use Mac OS, you can install the Xcode Command Line Tools by running the following command in the terminal:

$ xcode-select –install

If you use Mac OS on an Apple silicon machine, you also need to install Rosetta for x86 emulation. You should verify that clang can generate x86-64 code and Rosetta emulation works correctly:

$ echo "#include <stdio.h>\nint main() { printf(\"Hello\"); return 0; }" > hello.c
$ clang -arch x86_64 hello.c -o hello
$ ./hello
Hello%

You should see the output Hello.

4 Editors and IDEs🔗

You may use any text editors or IDEs of your choice for writing Scala and C code.

Some popular choices include: VSCode, Vim/NeoVim, Emacs, IntelliJ IDEA (with Scala plugin).

For VSCode, you may want to install the official Scala syntax extension. Optionally, Metals is a popular language server for Scala that provides IDE-like features with in various editors.