* [Building](#building)
  * [Common Gradle Tasks](#common-gradle-tasks)
  * [Developing in IntelliJ IDEA](#developing-in-intellij-idea)
* [Project Structure](#project-structure)
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* [Contributing Guidelines](#contributing-guidelines)
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# Building

We use gradle to build the compiler. It comes with a wrapper script (`gradlew` or `gradlew.bat` in
the root of the repository) which downloads appropriate version of gradle
automatically as long as you have JDK (version >= 11) installed.

## Common Gradle Tasks

All gradle tasks are case-insensitive.

|Command|Description|
|:---|:---|
|`./gradlew :cli:jarDep`|build a jar file which includes all the dependencies which can be found at `cli/build/libs`.<br/>A short-hand version of this task is `./gradlew jarDep`.|
|`./gradlew :cli:copyJarDep`|build `jarDep` and copy it to the current directory.<br/>A short-hand version of this task is `./gradlew copyJarDep`.|
|`./gradlew :api:assemble`|build Arend extension API jar which can be found at `api/build/libs`.|
|`./gradlew test`|run all tests.|

On Windows, you may replace `./gradlew` with `gradlew`.

To see the command line options of the application, run `java -jar cli-[version]-full.jar --help`
after running the `jarDep` task.

## Developing in IntelliJ IDEA

Here's an [instruction](https://www.jetbrains.com/help/idea/gradle.html)
on how to work with gradle projects in IntelliJ IDEA.

You may also need the following plugins:
+ Gradle and Groovy -- bundled plugins, needed for building the project
+ [ANTLR v4 grammar](https://plugins.jetbrains.com/plugin/7358) for editing the parser
+ [Protobuf](https://plugins.jetbrains.com/plugin/8277) for editing the serialized protobuf
+ [Kotlin](https://plugins.jetbrains.com/plugin/6954) for editing the build scripts
+ [Arend](https://plugins.jetbrains.com/plugin/11162) for editing Arend code

# Project Structure

Arend is split into several subprojects:

|Subproject|Description|
|:---:|:---|
|`buildSrc`|built before the project is built.<br/>This subproject runs the ANTLR parser generator.|
|`parser`|the generated ANTLR parser (the generation is done in `buildSrc`)|
|`proto`|generated protobuf classes.|
|`api`|open API for writing Arend extensions.|
|`base`|the Arend typechecker.<br/>It depends on `api`, `proto`.|
|`cli`|the CLI frontend of Arend with the ANTLR parser.<br/>It depends on `base`, `parser`, `api`, `proto`.|

The purpose of `parser` is to avoid introducing the dependency of the ANTLR
generator to other subprojects which only requires
the generated parser along with a small ANTLR runtime
(since it's a dependency of `buildSrc` instead of `parser`).

The root project contains all the tests,
and it depends on project `cli`.
The tests are based on JUnit 4.
If you want to move tests to a separate subproject, we wish you good luck.

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# Contributing Guidelines

Things to keep in mind:

+ Don't refactor others' code, but you're welcomed to refactor your own.
+ Add a test fixture when you fix a bug to ensure it never popups again.
+ Make sure tests pass before submitting a patch or a pull request.
  Your code will be tested on GitHub Actions.
+ Be careful when you want to modify the build scripts,
  make sure dependencies shared by multiple subprojects have a corresponding
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+ [JetBrains Annotations](https://github.com/JetBrains/java-annotations) is your friend.
+ Never add generated files to the git repo.

If you don't know where to start but looking for a chance of contribution,
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one you like. You can ask a developer on [gitter](https://gitter.im/arend-lang/community).
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