scala-cli

Scala CLI is an experimental tool to run/compile/test Scala that aims at being a better scala command. It shares some similarities with build tools, but doesn't aim at supporting multi-module projects, nor to be extended via a task system.

User-facing documentation can be found on our website: scala-cli.virtuslab.org.

Developer docs

Requirements

Building Scala CLI requires a JVM 17 to work properly.

In theory, our build is able to download and install for its own needs JVM 17 on some OSes however it may not work in Intellij / Metals out of the box.

The Scala CLI sources ship with Mill launchers, so that Mill itself doesn't need to be installed on your system.

Common commands

Running the CLI from sources

./mill -i scala …arguments…

Run unit tests

./mill 'build[_].test'

Run integration tests with the JVM launcher

./mill integration.jvm.test

Filter test suites with

./mill integration.jvm.test 'scala.cli.integration.RunTests.*'
./mill integration.jvm.test 'scala.cli.integration.RunTests.Multiple scripts'

Run integration tests with the native launcher

(generating the launcher can take several minutes)

./mill integration.native.test

Generate native packages

Build native packagers:

deb for linux
msi for windows
dmg and pkg for macOS

(generating native packager for specified format)

./mill -i scala package ..arguments... --deb --output 'path.deb'
./mill -i scala package ..arguments... --dmg --output 'path.dmg'
./mill -i scala package ..arguments... --pkg --output 'path.pkg'

Generate Metals configuration files

./mill mill.contrib.Bloop/install

Then run the command "Metals: Connect to build server".

(Recommended over the Metals import project functionality.)

Whenever the build is updated, just do these two steps again.

Generate IntelliJ configuration files

./mill mill.scalalib.GenIdea/idea

Then open the scala-cli directory in IntelliJ.

(Recommended over the IntelliJ import project functionality.)

Whenever the build is updated, run the command above again. IntelliJ should then pick up the new changes.

Generate a native launcher

./mill -i show cli.nativeImage

This prints the path to the generated native image. The file named scala at the root of the project should also be a link to it. (Note that the link is committed and is always there, whether the files it points at exists or not.)

Generate a JVM launcher

./mill -i show cli.launcher

This prints the path to the generated launcher. This launcher is a JAR, that directly re-uses the class directories of the modules of the project (so that cleaning up those classes will break the launcher). If this is a problem (if you wish to run the launcher on another machine or from a Docker image for example), use a native launcher (see above) or a standalone JVM one (see below).

Generate a standalone JVM launcher

./mill -i show cli.standaloneLauncher

This prints the path to the generated launcher. This launcher is a JAR, that embeds JARs of the scala-cli modules, and downloads their dependencies from Maven Central upon first launch (using the coursier cache, just like a coursier bootstrap).

Website

The Scala CLI website is built with Docusaurus and uses Infima for styling.

Generate the website once

cd website
yarn build
npm run serve

Generate the website continuously

cd website
yarn run start

Verifying the documentation

We have a built-in tool to validate .md files called Sclicheck. To check all douments (and this is what we run on CI) run:

.github/scripts/check_docs.sh

You can also check single documents or directories using

.github/scripts/check_docs.sh <file> <dir>

To debug failing document, Sclicheck has build-in following options: --step (stop after each command) or --stopAtFailure (to stop after a failure). To debug getting started guide run following command:

.github/scripts/check_docs.sh --stopAtFailure docs/getting_started.md

Scala CLI logos

Package with various logos for scala-cli can be found on google drive

Launcher script

There is a script scala-cli-src in the repository root that is intended to work exactly like released scala-cli, but using a binary compiled the worktree. Just add it to your PATH to get the already-released-scala-cli experience.

Releases

Instructions on how to release - Release Procedure

Debugging BSP server

The easiest way to debug BSP sever is using scala-cli-src script with --bsp-debug-port 5050 flag (the port should be unique to the workspace where BSP will be debugged). In such case BSP will be launched using local source and will run on JVM. It will also expects a debugger running in the listen mode using provided port (so the initialization of the connection can be debugged). In such case we recommend to have option to auto rerun debugging session off (so there is always a debugger instance ready to be used).

algobardo/scala-cli-1