Kotlin Programming Language
Welcome to Kotlin! Some handy links:
- Kotlin Site
- Getting Started Guide
- Try Kotlin
- Kotlin Standard Library
- Issue Tracker
- Kotlin Blog
- Follow Kotlin on Twitter
- Public Slack channel
- TeamCity CI build
Build environment requirements
In order to build Kotlin distribution you need to have:
Apache Ant 1.9.4 and higher
JDK 1.6, 1.7 and 1.8
Setup environment variables as following:
JAVA_HOME="path to JDK 1.8" JDK_16="path to JDK 1.6" JDK_17="path to JDK 1.7" JDK_18="path to JDK 1.8"
For local development, if you're not working on bytecode generation or the standard library, it's OK to have only JDK 8 installed, and to point all of the environment variables mentioned above to your JDK 8 installation.
You also can use Gradle properties to setup JDK_* variables.
Note: The JDK 6 for MacOS is not available on Oracle's site. You can download it here.
To build this project, first time you try to build you need to run this:
ant -f update_dependencies.xml
which will setup the dependencies on
intellij-coreis a part of command line compiler and contains only necessary APIs.
idea-fullis a full blown IntelliJ IDEA Community Edition to be used in the plugin module.
Then, you may run Gradle to build the project and run tests, using:
command on Unix/macOS, or
Important gradle tasks
clean- clean build results
dist- assembles the compiler distribution into
ideaPlugin- assembles the Kotlin IDEA plugin distribution into
install- build and install all public artifacts into local maven repository
runIde- build IDEA plugin and run IDEA with it
coreLibsTest- build and run stdlib, reflect and kotlin-test tests
gradlePluginsTest- build and run gradle plugin tests
compilerTest- build and run all compiler tests
ideaPluginTest- build and run all IDEA plugin tests
OPTIONAL: Some artifacts, mainly Maven plugin ones, are built separately by Maven: go into
libraries directory after building the compiler and run:
Refer to libraries/ReadMe.md for details.
Working with the project in IntelliJ IDEA
Working with the Kotlin project requires IntelliJ IDEA 2017.3. You can download an Early Access Preview version of IntelliJ IDEA 2017.3 here.
To import the project in Intellij choose project directory in Open project dialog. Then, after project opened, Select
Module from Existing Sources in the menu, and select
build.gradle.kts file in the project's root folder.
In the import dialog, select
use default gradle wrapper.
To be able to run tests from IntelliJ easily, check
Delegate IDE build/run actions to Gradle in the Gradle runner settings.
At this time, you can use the latest released 1.1.x version of the Kotlin plugin for working with the code. To make sure you have the latest version installed, use Tools | Kotlin | Configure Kotlin Plugin Updates and press "Check for updates now".
Compiling and running
From this root project there are Run/Debug Configurations for running IDEA or the Compiler Tests for example; so if you want to try out the latest and greatest IDEA plugin
- VCS -> Git -> Pull
- Run the "IDEA" run configuration in the project
- a child IntelliJ IDEA with the Kotlin plugin will then startup
We love contributions! There's lots to do on Kotlin and on the standard library so why not chat with us about what you're interested in doing? Please join the #kontributors channel in our Slack chat and let us know about your plans.
If you want to find some issues to start off with, try this query which should find all Kotlin issues that marked as "up-for-grabs".
Currently only committers can assign issues to themselves so just add a comment if you're starting work on it.
A nice gentle way to contribute would be to review the standard library docs and find classes or functions which are not documented very well and submit a patch.
In particular it'd be great if all functions included a nice example of how to use it such as for the
This is implemented using the
@sample macro to include code from a test function. The benefits of this approach are twofold; First, the API's documentation is improved via beneficial examples that help new users and second, the code coverage is increased.
Some of the code in the standard library is created by generating code from templates. See the README in the stdlib section for how run the code generator. The existing templates can be used as examples for creating new ones.
If you create your own fork, it might help to enable rebase by default when you pull by executing
git config --global pull.rebase true
This will avoid your local repo having too many merge commits which will help keep your pull request simple and easy to apply.