# Contributing to Enso Thank you for your interest in contributing to Enso! We believe that only through community involvement can Enso be the best it can be! There are a whole host of ways to contribute, and every single one is appreciated. The major sections of this document are linked below: - [The Contributor License Agreement](#the-contributor-license-agreement) - [Issues](#issues) - [Feature Enhancements](#feature-enhancements) - [Bug Reports](#bug-reports) - [Hacking on Enso](#hacking-on-enso) - [Pull Requests](#pull-requests) - [Documentation](#documentation) - [Issue Triage](#issue-triage) - [Out-of-Tree Contributions](#out-of-tree-contributions) - [Helpful Documentation and Links](#helpful-documentation-and-links) All contributions to Enso should be in keeping with our [Code of Conduct](https://github.com/luna/luna/blob/CODE_OF_CONDUCT.md). ## The Contributor License Agreement As part of your first contribution to this repository, you need to accept the Contributor License Agreement. You will automatically be asked to sign the CLA when you make your first pull request. Any work intentionally submitted for inclusion in Enso shall be licensed under this CLA. The CLA you sign applies to all repositories associated with the Enso project, so you will only have to sign it once at the start of your contributions. ## Issues If you are looking for somewhere to start, check out the `Help Wanted` tag in the following repositories: - [Enso](https://github.com/luna/enso/labels/Status%3A%20Help%20Wanted) - [Enso Studio](https://github.com/luna/ide/labels/Status%3A%20Help%20Wanted) ## Feature Enhancements If you feel like you have a suggestion for a change to the way that Enso works as a language, please open an issue in our [RFCs Repository](https://github.com/luna/luna-rfcs), rather than in this one! New features and other significant language changes must go through the RFC process so they can be properly discussed. ## Bug Reports While it's never great to find a bug, they are a reality of software and software development! We can't fix or improve on the things that we don't know about, so report as many bugs as you can! If you're not sure whether something is a bug, file it anyway! **If you are concerned that your bug publicly presents a security risk to the users of Enso, please contact [security@luna-lang.org](mailto:security@luna-lang.org).** Even though GitHub search can be a bit hard to use sometimes, we'd appreciate if you could [search](https://github.com/luna/enso/search?q=&type=Issues&utf8=%E2%9C%93) for your issue before filing a bug as it's possible that someone else has already reported the issue. We know the search isn't the best, and it can be hard to know what to search for, so we really don't mind if you do submit a duplicate! Opening an issue is as easy as following [this link](https://github.com/luna/enso/issues/new?template=bug-report.md) and filling out the fields. The template is intended to collect all the information we need to best diagnose the issue, so please take the time to fill it out accurately. The reproduction steps are particularly important, as the more easily we can reproduce it, the faster we can fix the bug! It's also helpful to have the output of `enso --version`, as that will let us know if the bug is Operating System or Architecture specific. ## Hacking on Enso This will get you up and running for Enso development, with only a minimal amount of setup required. Enso's build system is fairly simple, allowing you to bootstrap the compiler as long as you have... ### Design Documentation If you're going to start contributing to Enso, it is often a good idea to take a look at the design documentation for the language. These files explain provide both a rigorous specification of Enso's design, but also insight into the _why_ behind the decisions that have been made. These can be found in [`doc/design/`](doc/design/), and are organised by the part of the compiler that they relate to. ### System Requirements In order to build and run Enso you will need the following tools: - [sbt](https://www.scala-sbt.org/) with version at least 1.3.0. - [GraalVM](https://www.graalvm.org/) with version at least that described in the [`build.sbt`](build.sbt) file configured as your default JVM. [Jenv](http://www.jenv.be/) is a useful tool for managing multiple JVMs. ### Getting the Sources Given you've probably been reading this document on GitHub, you might have an inkling where to look!. You can clone Enso using two methods: - **Via HTTPS:** We recommend you only use HTTPS if checking out the sources as read-only. ``` git clone https://github.com/luna/enso.git ``` - **Via SSH:** For those who plan on regularly making direct commits, cloning over SSH may provide a better user experience (but requires setting up your SSH Keys with GitHub). ``` git clone git@github.com:luna/enso.git ``` ### Building Enso There are multiple projects in this repository, but all can be built, run and tested using `sbt`. As long as your configuration is correct, with the correct versions of SBT and GraalVM, the same steps can be followed on all of our supported platforms (Linux, MacOS and Windows). SBT will handle downloading and building library dependencies as needed, meaning that you don't need to handle any of this manually. **Please note** that at the current time, the Windows build of GraalVM is in an experimental state. This means that while it may function, we are not intending to provide work-arounds for building on that platform while it is still in an unstable state. #### Building Enso Components In order to build a specific component (e.g. `runtime`), please follow the following steps. 1. Enter the sbt shell in the repository root directory by typing `sbt`. 2. Change to the project you are concerned with (in our case `runtime`) by executing `project runtime`. 3. Execute `compile` in order to compile the project in question. This will compile the project and all its dependencies as necessary. You can substitute both `bench` and `test` for `compile` in step 3, and the sbt shell will execute the appropriate thing. Furthermore we have `testOnly` and `benchOnly` that accept a glob pattern that delineates some subset of the tests or benchmarks to run (e.g. `testOnly *FunctionArguments*`). #### Building the Interpreter CLI Fat Jar In order to build a fat jar with the CLI component, run the `assembly` task inside the `runtime` subproject: ```bash sbt "runtime/assembly" ``` This will produce an executable `enso.jar` fat jar in the repository root. It's self contained, with its only dependencies being available inside a vanilla GraalVM distribution. To run it, use: ```bash JAVA_HOME= ./enso.jar ``` If you decide not to use the default launcher script, make sure to pass the `-XX:-UseJVMCIClassLoader` option to the `java` command. #### Installing the Jupyter kernel Enso has a highly experimental and not-actively-maintained Jupyer Kernel. To run it: 1. Build (or download from the CI server) the CLI Fat Jar. 2. Fill in the `engine/language-server/jupyter-kernel/enso/kernel.json` file, providing correct paths to the `enso.jar` distribution and GraalVM `JAVA_HOME`. 3. Run: ```bash jupyter kernelspec install /engine/language-server/jupyter-kernel/enso ``` Congratulations, your Jupyter Kernel should now be installed and ready to use. #### Passing Debug Options GraalVM provides some useful debugging options, including the ability to output the compilation graph during JIT optimisation, and the ASM generated by the JIT. However, as we don't want these things polluting our standard builds, we provide a helper SBT command `withDebug` to allow for passing these options. It supports the following flags: - `--dumpGraphs`: This dumps the IGV (a Graal tool) graphs for the program to allow for manual analysis and discovery of optimisation failures. - `--showCompilations`: Prints the truffle compilation trace information. - `--printAssembly`: Prints the assembly output from the HotSpot JIT tier. For more information on this sbt command, please see [WithDebugCommand.scala](project/WithDebugCommand.scala). It is used as an addendum to the basic sbt command you want to run (e.g. `test` from above). The format is `withDebug COMMAND [OPTIONS...]`, and if you need to pass any additional options to `COMMAND` you must do so following a `--`. For example: ``` withDebug run --dumpGraphs --printAssembly -- --run MyFile.enso withDebug benchOnly --showCompilations -- RecursionBenchmark ``` #### Working with Assembly In order to examine the assembly generated by GraalVM and HotSpot you need to provide your JVM install with a dynamic library that supports the dumping of assembly. It can be acquired for MacOS and Linux [here](https://github.com/liuzhengyang/hsdis/), and for windows from [here](http://fcml-lib.com/). There are other methods to acquire it, as well, so please choose one best suited for you. Once you have a copy of the dynamic library, it needs to be placed in `$JVM_HOME/jre/lib/server` on a JDK-8 install, or in `$JVM_HOME/lib/server` for a JDK-10 or later install. #### Native Image Native image is a capability provided alongside GraalVM that allows the generation of native executables from JVM language programs (such as the Enso interpreter itself). However, it results in significantly degraded peak performance, so it is not part of our roadmap currently. If you would like to experiment with it, you can execute the `buildNativeImage` command in the sbt shell while inside the `runner` project. Please note that while the command is available at the moment, and you are welcome to [report an issue](https://github.com/luna/enso/issues/new?assignees=&labels=Type%3A+Bug&template=bug-report.md&title=) with the functionality, any bugs you report will _not_ be considered high priority. **WE CURRENTLY DO NOT SUPPORT THE NATIVE IMAGE BUILD.** #### Using IntelliJ Internally, most of the developers working on the Enso project use IntelliJ as their primary IDE. To that end, what follows is a basic set of instructions for getting the project into a working state in IntelliJ. 1. Clone the project sources. 2. Open IntelliJ 3. File -> New -> Project From Existing Sources. 4. Navigate to the directory into which you cloned the project sources. By default this will be called `enso`. Select the directory, and not the `build.sbt` file it contains. 5. In the 'Import Project' dialogue, select 'Import project from external model' and choose 'sbt'. 6. Where it says 'Download:', ensure you check both 'Library Sources' and 'sbt sources'. 7. In addition, check the boxes next to 'Use sbt shell:' such that it is used both 'for imports' and 'for builds'. 8. Disallow the overriding of the sbt version. 9. Under the 'Project JDK' setting, please ensure that it is set up to use a GraalVM version as described in [Requirements](#requirements). You may need to add it using the 'New' button if it isn't already set up. 10. Click 'Finish'. This will prompt you as to whether you want to overwrite the `project` folder. Select 'Yes' to continue. The Enso project will load up with an open SBT shell, which can be interacted with as described above. You will want to use scalafmt for formatting of Scala code, and install Google Java Format for formatting Java code. For more information see the relevant [Style Guides](doc/). However, as mentioned in the [Troubleshooting](#troubleshooting) section below, the forked nature of execution in the SBT shell means that we can't trivially make use of the IntelliJ debugger. In order to get debugging working, you will need to follow these steps: 1. Go to Run -> Edit Configurations. 2. Click the `+` button in the header of the 'Run/Debug Configurations' dialogue that pops up. 3. Select 'Remote' and name the new configuration appropriately. 4. In the options for that configuration select 'Listen to remote JVM' under 'Debugger mode:' 5. Where it provides the command-line arguments for the remote JVM, copy these and add them to `truffleRunOptions` in [`build.sbt`](build.sbt). Remove the portion of these options after `suspend=y`, including the comma. They are placeholders that we don't use. 6. Now, when you want to debug something, you can place a breakpoint as usual in IntelliJ, and then execute your remote debugging configuration. Now, in the SBT shell, run a command to execute the code you want to debug (e.g. `testOnly *CurryingTest*`). This will open the standard debugger interface and will allow you to step through your code. **Please be careful** to ensure that you don't commit these changes to the sbt configuration as they are specific to your machine. #### Troubleshooting If you are having issues building Enso, please check the list below before filing an issue with us. - **`StackOverflowError` During Compilation:** Please ensure that your version of sbt is respecting the project's `.jvmopts` settings. We make significant use of recursion when expanding macros for the parser, and these require use of additional stack. Alternatively, you can explicitly pass `-Xss8M` to the `sbt` invocation. - **Debugging Not Working:** The sbt tasks run the invoked programs in a forked JVM. This means that to attach a debugger to it you need to use the JVM remote debugging support. We cannot support all possible configurations for this, but if you use IntelliJ please see the [Using IntelliJ](#using-intellj) section above for instructions. If your problem was not listed above, please [file a bug report](https://github.com/luna/enso/issues/new?assignees=&labels=Type%3A+Bug&template=bug-report.md&title=) in our issue tracker and we will get back to you as soon as possible. ### Running Enso The only component in this repository with a proper executable is the Enso interpreter. It can be run using the sbt `run` command in the project `runner` and provides a rudimentary command-line interface to the basic capabilities of the interpreter. Detailed information on the flags it supports can be obtained by executing `run --help`, but the primary functionality is as follows: - `--new PATH`: Creates a new Enso project at the location spcified by `PATH`. - `--run PATH`: Executes the interpreter on the Enso source specified by `PATH`. In this case, `PATH` must point to either a standalone Enso file or an Enso project. #### Language Server Mode The Language Server can be run using the `--server` option. It requires also a content root to be provided (`--root-id` and `--path` options). Command-line interface of the runner prints all server options when you execute it with `--help` option. Below are options uses by the Language Server: - `--server`: Runs the Language Server - `--root-id `: Content root id. - `--path `: Path to the content root. - `--interface `: Interface for processing all incoming connections. Default value is 127.0.0.1 - `--port `: Port for processing all incoming connections. Default value is 8080. To run the Language Server on 127.0.0.1:8080 type: ```bash java -jar enso.jar \ --server \ --root-id 3256d10d-45be-45b1-9ea4-7912ef4226b1 \ --path /tmp/content-root ``` If you want to provide a socket that the server should listen to, you must specify the following options: - `--interface`: The interface on which the socket will exist (e.g. `0.0.0.0`). - `--port`: The port on `interface` where the socket will be opened (e.g. `80`). ## Pull Requests Pull Requests are the primary method for making changes to Enso. GitHub has [fantastic documentation](https://help.github.com/articles/about-pull-requests/) on using the pull request feature. Enso uses the 'fork-and-pull' model of development. It is as described [here](https://help.github.com/articles/about-collaborative-development-models/) and involves people pushing changes to their own fork and creating pull requests to bring those changes into the main Enso repository. Please make all pull requests against the `master` branch. - We enforce a strict review-before-CI policy for external contributions, but we do ask that you make sure to run the test suite locally. This can be done by running `test` in the `enso` project in sbt. - Additionally, please ensure that your code conforms to the Enso style guides, particularly the [Scala Style Guide](./doc/scala-style-guide.md) and the [Java Style Guide](./doc/java-style-guide.md). Make sure you perform these checks before _every_ pull request. You can even add [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks) before every push to make sure that you can't forget. - Every pull request to the Enso repository is reviewed by a member of the core team! You'll get assigned a reviewer based on the areas your PR touches, but please feel free to ask for a specific person if you've worked with them in a specific area before! - If you have questions, or would like to begin the review process before your PR is 'done', please use the [Draft Pull Requests](https://github.blog/2019-02-14-introducing-draft-pull-requests/) feature on GitHub. Once the reviewer approves your pull request it will be tested by our continuous integration provider before being merged. If we request changes to your PR, please feel free to discuss the suggestions and comments! We can only achieve the best results through open collaboration. ## Documentation Documentation improvements are very welcome! The source for the Enso, Book can be found in [`luna/luna-book`](https://github.com/luna/luna-book), but most of the API documentation is generated directly from the code! Documentation pull requests are reviewed in exactly the same way as normal pull requests. To find documentation-related issues, sort by the [Category: Documentation](hhttps://github.com/luna/enso/labels/Category%3A%20Documentation) label. ## Issue Triage Sometimes issues can be left open long after the bug has been fixed. Other times, a bug might go stale because something has changed in the meantime. It can be helpful to go through older bug reports and make sure that they are still valid. Load up an older issue, double check that it's still true, and leave a comment letting us know if it is or is not. The [least recently updated](https://github.com/luna/enso/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc) sort is good for finding issues like this. Contributors with sufficient permissions can help by adding labels to help with issue triage. If you're looking for somewhere to start, take a look at the [Difficulty: Beginner](https://github.com/luna/enso/labels/Difficulty%3A%20Beginner) issue label, as well as the [Status: Help Wanted](https://github.com/luna/enso/labels/Status%3A%20Help%20Wanted) label. ## Out-of-Tree Contributions As helpful as contributing to Enso directly is, it can also be just as helpful to contribute in other ways outside this repository: - Answer questions in the [Discord](https://discordapp.com/invite/YFEZz3y) or on [StackOverflow](https://stackoverflow.com/questions/tagged/luna). - Participate in the [RFC Process](https://github.com/luna/luna-rfcs). ## Helpful Documentation and Links For people new to Enso, and just starting to contribute, or even for more seasoned developers, some useful places to look for information are: - [The Enso Book](https://luna-lang.gitbooks.io/docs/) - The community! Don't be afraid to ask questions.