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
- Feature Enhancements
- Bug Reports
- Hacking on Enso
- Pull Requests
- Issue Triage
- Out-of-Tree Contributions
- Helpful Documentation and Links
All contributions to Enso should be in keeping with our Code of Conduct.
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.
If you’re wanting to get involved with Enso’s development and are looking for somewhere to start, you can check out the following tags in our issues:
You can use the “Size” and “Difficulty” labels that should be assigned to every issue to get a better idea of how much work a given issue might be.
If you feel like you have a suggestion for a change to the way that Enso works as a language, please take a look at the Enso RFC process to learn how to file an RFC for the project.
In essence, the RFC process provides a way to propose major changes to the language, the compiler, and the runtime in a way that ensures that they get seen and discussed by all the major stakeholders involved.
If, on the other hand, you’re asking for a smaller feature, please feel free to submit a feature request to the repository.
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 look at our security guidelines.
Even though GitHub search can be a bit hard to use sometimes, we’d appreciate if you could search 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 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
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 a minimal set of tools.
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
docs/, and are organised by the part of the
compiler that they relate to.
The following operating systems are supported for developing Enso:
- Windows 10
- macOS 10.14 and above
- Linux 4.4 and above
Currently only the x86_64 (amd64) architecture is supported. You may be able to develop Enso on other systems, but issues arising from unsupported configurations will not be fixed by the core team.
In order to build and run Enso you will need the following tools:
- sbt with the same version as specified in
- Maven with version at least 3.6.3.
- GraalVM with the same version as described in the
build.sbtfile, configured as your default JVM. GraalVM is distributed for different Java versions, so you need a GraalVM distribution for the same Java version as specified in
- Flatbuffers Compiler with version 1.12.0.
- Cargo, the rust build tool.
- Rustup, the rust toolchain management utility.
- On MacOS and Linux, the
tarcommand is required for running some tests. It should be installed by default on most distributions.
- If you want to be able to build the Launcher Native Image, you will need a
native C compiler for your platform as described in the
Native Image Prerequisites.
On Linux that will be
gcc, on macOS you may need
xcodeand on Windows you need to configure the Developer Command Prompt for Microsoft Visual C++ for the x64 architecture.
Managing multiple JVM installations can be a pain, so some of the team use Jenv: A useful tool for managing multiple JVMs.
flatc compiler can be installed from the following locations:
- Using the
condapackage manager (
conda install flatbuffers). This will work on all platforms, but requires some knowledge of
condaand how its environments work.
- Windows users can download binaries directly from the flatbuffers github releases.
- MacOS users can install it via homebrew (
brew install flatbuffers).
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/enso-org/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 email@example.com:enso-org/enso.git
Getting Set Up (Rust)
The SBT project requires a specific nightly rust toolchain. To get it set up, you will need to install rustup and then run the following commands:
rustup toolchain install nightly-2021-05-12 rustup override set nightly-2021-05-12 rustup component add clippy
Getting Set Up (JVM)
In order to properly build the
runtime component, the JVM running SBT needs to
have some dependency JARs available in its module path at startup. To ensure
they are available, before running any compilation or other tasks, these
dependencies should be prepared. To do so, run the following command in the
repository root directory:
It is preferred to not run this command from the sbt shell, but in batch mode, because SBT has to be launched again anyway to pick up these JARs at startup.
Bootstrap has to be run only when building the project for the first time and after each change of Graal version.
Getting Set Up (Documentation)
We enforce automated formatting of all of our documentation and configuration using the fairly common prettier automatic formatter. You can install prettier for our project by running the following command:
This does, however, mean that you have to have node installed on your system. Please follow the guidelines above to install node if you have not already done so.
The version if prettier is forced by our
package-lock.json in order for us to make formatting
bumps all at once.
You can format all of our documentation and configuration as follows:
npx prettier --write <dir>
There are multiple projects in this repository, but all can be built, run and
sbt. As long as your configuration is correct, with the correct
versions of SBT, Rust 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
- Enter the sbt shell in the repository root directory by typing
- Change to the project you are concerned with (in our case
runtime) by executing
compilein order to compile the project in question. This will compile the project and all its dependencies as necessary.
You can substitute both
compile in step 3, and the sbt
shell will execute the appropriate thing. Furthermore we have
benchOnly that accept a glob pattern that delineates some subset of the tests
or benchmarks to run (e.g.
Building the Interpreter CLI Fat Jar
In order to build a fat jar with the CLI component, run the
This will produce an executable
runner.jar fat jar and a
runtime.jar fat jar
in the repository root. The
runner.jar depends only on the
runtime.jar and a
vanilla GraalVM distribution.
Building the Project Manager Fat Jar
In order to build a fat jar with the Project Manager component, run the
assembly task on the
This will produce a
project-manager fat jar and a
runtime.jar fat jar in the
Building the Launcher Native Binary
If you want to build the native launcher binary, you need to ensure that the Native Image component is installed in your GraalVM distribution. To install it, run:
<path-to-graal-home>/bin/gu install native-image
Then, you can build the launcher using:
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.
It is used as an addendum to the basic sbt command you want to run (e.g.
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
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, and for windows from here. 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
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
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
with the functionality, any bugs you report will not be considered high
WE CURRENTLY DO NOT SUPPORT THE NATIVE IMAGE BUILD.
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.
- Clone the project sources.
- Open IntelliJ
- File -> New -> Project From Existing Sources.
- 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.sbtfile it contains.
- In the ‘Import Project’ dialogue, select ‘Import project from external model’ and choose ‘sbt’.
- Where it says ‘Download:’, ensure you check both ‘Library Sources’ and ‘sbt sources’.
- In addition, check the boxes next to ‘Use sbt shell:’ such that it is used both ‘for imports’ and ‘for builds’.
- Disallow the overriding of the sbt version.
- Under the ‘Project JDK’ setting, please ensure that it is set up to use a GraalVM version as described in System requirements. You may need to add it using the ‘New’ button if it isn’t already set up.
- Click ‘Finish’. This will prompt you as to whether you want to overwrite the
projectfolder. 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.
Depending on the version of GraalVM with which you are working, you may be
required to add the following flags to the per-module overrides for IntelliJ’s
java compiler in order for it to not show spurious errors. This is because some
versions of GraalVM export their own closed version of
that IntelliJ picks up preferentially to the version we use for development. You
can find these options in
Preferences -> Build, Execution, Deployment -> Compiler -> Java Compiler.
--add-exports org.graalvm.truffle/com.oracle.truffle.api=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.debug=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.dsl=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.exception=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.frame=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.instrumentation=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.interop=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.io=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.library=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.memory=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.nodes=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.object=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.profiles=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.source=ALL-UNNAMED --add-exports org.graalvm.truffle/com.oracle.truffle.api.utilities=ALL-UNNAMED
However, as mentioned in the 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:
- Go to Run -> Edit Configurations.
- Click the
+button in the header of the ‘Run/Debug Configurations’ dialogue that pops up.
- Select ‘Remote’ and name the new configuration appropriately.
- In the options for that configuration select ‘Listen to remote JVM’ under ‘Debugger mode:’
- Where it provides the command-line arguments for the remote JVM, copy these
and add them to
build.sbt. Remove the portion of these options after
suspend=y, including the comma. They are placeholders that we don’t use.
- Alternatively, certain tasks, such as
testOnlycan be used through the
withDebugSBT command. For this to work, your remote configuration must specify the host of
localhostand the port
5005. The command syntax is
withDebug --debugger TASK_NAME -- TASK_PARAMETERS, e.g.
withDebug --debugger testOnly -- *AtomConstructors*.
- 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.
If you are having issues building Enso, please check the list below before filing an issue with us.
StackOverflowErrorDuring Compilation: Please ensure that your version of sbt is respecting the project’s
.jvmoptssettings. We make significant use of recursion when expanding macros for the parser, and these require use of additional stack. Alternatively, you can explicitly pass
- 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 section above for instructions.
If your problem was not listed above, please file a bug report in our issue tracker and we will get back to you as soon as possible.
Running the tests for the JVM enso components is as simple as running
sbt / test. To test the Rust components you can run
cargo test. Finally, you
can run the WASM tests for the rust components by using
Testing Enso Libraries
To test the libraries that are shipped with Enso you need to first build the
engine, the easiest way to do so is to run
sbt buildEngineDistribution. That
will create a distribution in the directory
built-distribution. The engine
runner that can be used for running the tests is located at
enso.bat for Windows).
To run the tests you can run the following commands (where
enso refers to the
built runner executable as explained above):
enso --run test/Tests # for the Base library enso --run test/Geo_Tests enso --run test/Table_Tests enso --run test/Database_Tests
The Database tests will by default only test the SQLite backend, to test other
for information on how to configure them.
The Base tests rely in a few places on the system language. On Linux you can set
LANG environment variable to
C to make sure that the language is
configured correctly and run the tests as following:
LANG=C enso --run test/Tests
Some test suites require extra setup and enabled only on CI. To replicate the CI environment you should install and run extra services:
# Httpbin go get -v github.com/ahmetb/go-httpbin/cmd/httpbin $(go env GOPATH)/bin/httpbin -host :8080
To run all the stdlib test suites, set
CI=true environment variable:
env CI=true enso --run test/Tests/
For more details about the CI setup, you can check the
.github/workflows/scala.yml GitHub workflow.
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
and provides a rudimentary command-line interface to the basic capabilities of
Enso should be launched using the
Interpreter is started with the
distribution/bin/enso script and requires
Building the Interperter CLI Fat Jar)
to be built and copied (or linked) to the
# build runtime.jar and runner.jar sbt engine-runner/assembly # link or copy jars to the distributiong mkdir -p distribution/component cd distribution/component ln -s ../../runtime.jar . ln -s ../../runner.jar .
# build runtime.jar and runner.jar sbt.bat engine-runner/assembly # copy jars to the distributiong mkdir -p .\distribution\component cp .\runtime.jar .\distribution\component\ cp .\runner.jar .\distribution\component\
Detailed information on the flags it supports is shown by the
--help flag, but
the primary functionality is as follows:
--new PATH: Creates a new Enso project at the location spcified by
--run PATH: Executes the interpreter on the Enso source specified by
PATH. In this case,
PATHmust point to either a standalone Enso file or an Enso project.
distribution/bin/enso --new ~/Hello distribution/bin/enso --run ~/Hello Hello, World!
distribution/bin/enso.bat --new ~/Hello distribution/bin/enso.bat --run ~/Hello Hello, World!
You can start IDE with a development version
of the language server. IDE executable has
--no-backend flag that switches off
the bundled backend. That requires you to run the project manager process
yourself. You can either get a project manager from one of the latest releases
on GitHub, or build one using SBT
When the command is completed, a development version of the project manager will
have appeared in the
The IDE will connect to the running project manager to look up the project and
start the language server. The required version of the language server is
specified in the
enso-version field of the
project.yaml project description
(Enso projects are located in the
name: Unnamed version: 0.0.1 enso-version: 0.0.0-SNAPSHOT license: "" authors:  maintainers: 
We need to set
enso-version to a value that will represent the development
version. It should be different from any Enso versions that have already been
released. In this case, we chose the
0.0.0-SNAPSHOT. The project manager will
look for the appropriate subdirectory in the engines directory of the
distribution folder. Distribution paths are printed when you run project manager
-v verbose logging.
$ ./built-distribution/enso-project-manager-0.2.12-SNAPSHOT-linux-amd64/enso/bin/project-manager -v [info] [2021-06-16T11:49:33.639Z] [org.enso.projectmanager.boot.ProjectManager$] Starting Project Manager... [debug] [2021-06-16T11:49:33.639Z] [org.enso.runtimeversionmanager.distribution.DistributionManager] Detected paths: DistributionPaths( dataRoot = /home/dbv/.local/share/enso, runtimes = /home/dbv/.local/share/enso/runtime, engines = /home/dbv/.local/share/enso/dist, bundle = None, config = /home/dbv/.config/enso, locks = /run/user/1000/enso/lock, tmp = /home/dbv/.local/share/enso/tmp )
On Linux it looks for the
We can build an engine distribution using the
And copy the result to the
0.0.0-SNAPSHOT engines directory of the
cp -r built-distribution/enso-engine-0.2.12-SNAPSHOT-linux-amd64/enso-0.2.12-SNAPSHOT ~/.local/share/enso/dist/0.0.0-SNAPSHOT
cp -r built-distribution/enso-engine-0.2.12-SNAPSHOT-linux-amd64/enso-0.2.12-SNAPSHOT ~/.local/share/enso/dist/0.0.0-SNAPSHOT
Now, when the project manager is running and the engines directory contains the
required engine version, you can start IDE with the
--no-backend flag. It will
pick up the development version of the language server we just prepared.
To summarize, these are the steps required to run IDE with the development version of the language server.
- Run the project manager process.
- Copy or symlink the development version of the engine created with SBT’s
buildEnginedistributioncommand to the engines directory of the Enso distribution folder.
- Set the
enso-versionfield of the
project.yamlproject definition to the version that you created in the previous step.
- Run the IDE with
Language Server Mode
The Language Server can be run using the
--server option. It requires also a
content root to be provided (
--path options). Command-line
interface of the runner prints all server options when you execute it with
Below are options uses by the Language Server:
--server: Runs the Language Server
--root-id <uuid>: Content root id.
--path <path>: Path to the content root.
--interface <interface>: Interface for processing all incoming connections. Default value is 127.0.0.1
--rpc-port <port>: RPC port for processing all incoming connections. Default value is 8080.
--data-port <port>: Data port for visualisation protocol. Default value is 8081.
To run the Language Server on 127.0.0.1:8080 type:
distribution/bin/enso \ --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.
--port: The port on
interfacewhere the socket will be opened (e.g.
Pull Requests are the primary method for making changes to Enso. GitHub has fantastic documentation on using the pull request feature. Enso uses the ‘fork-and-pull’ model of development. It is as described here 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
- We run CI on all contributions to Enso, but it’s still useful for you to run
the tests yourself locally first! This can be done by running
ensoproject in sbt.
- Additionally, please ensure that your code conforms to the Enso style guides, particularly the Scala Style Guide and the Java Style Guide.
Make sure you perform these checks before every pull request. You can even add 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 feature on GitHub. Doing so will allow you to make use of our CI infrastructure as part of your development process.
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 improvements are very welcome! For now, the main documentation
available is the developer documentation for the language, which can be found
at the dev docs site. The source for this
documentation is found in the
docs/ folder, and can be altered from
Documentation pull requests will be reviewed in exactly the same way as normal pull requests.
To find documentation-related issues, sort by the Category: Documentation label.
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 sort is good for finding issues like this.
Contributors with sufficient permissions can help by adding labels to help with issue triage.
As helpful as contributing to Enso directly is, it can also be just as helpful to contribute in other ways outside this repository:
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 design documentation.
- The community! Don’t be afraid to ask questions.