Scala Bazel Starter

# This is executable Markdown that's tested on CI.
# How is that possible? See https://gist.github.com/bwoods/1c25cb7723a06a076c2152a2781d4d49
set -o errexit -o nounset -o xtrace
alias ~~~=":<<'~~~sh'";:<<'~~~sh'

This repo includes:

• 🧱 Latest version of Bazel and dependencies
• 📦 Curated bazelrc flags via [bazelrc-preset.bzl]
• 🧰 Developer environment setup with [bazel_env.bzl]
• ✅ Pre-commit hooks for automatic linting and formatting
• 📚 Maven package manager integration

Note

You can customize languages and features with the interactive wizard in the aspect init command. init is an alternative to this starter repo, which was generated using the 'scala' preset. See https://docs.aspect.build/cli/overview

Setup dev environment

First, we recommend you setup a Bazel-based developer environment with direnv.

1. install https://direnv.net/docs/installation.html
2. run direnv allow and follow the prompts to bazel run //tools:bazel_env

This isn't strictly required, but the commands which follow assume that needed tools are on the PATH, so skipping direnv means you're responsible for installing them yourself.

Try it out

Create a minimal Scala application:

mkdir src
>src/Hello.scala cat <<EOF
object Hello {
  def main(args: Array[String]): Unit = {
    println("Hello from Scala")
  }
}
EOF

We didn't wire up the BUILD file generator for Scala yet (https://github.com/stackb/scala-gazelle) so we'll add this manually:

touch src/BUILD
buildozer 'new_load @rules_scala//scala:scala.bzl scala_binary' src:__pkg__
buildozer 'new scala_binary Hello' src:__pkg__
buildozer 'add srcs Hello.scala' src:Hello
buildozer 'set main_class Hello' src:Hello

Now the application should run, and we can verify it produced the expected output:

output="$(bazel run src:Hello)"

[ "${output}" = "Hello from Scala" ] || {
    echo >&2 "Wanted output 'Hello from Scala' but got '${output}'"
    exit 1
}