---
layout: developer-doc
title: Development & Contributing Guide
category: summary
tags: [summary, contributing]
---

# Development & Contributing Guide

Thank you for your interest in contributing to the Enso IDE! 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.

<br/>

## Reporting Issues

**If you are concerned that your bug publicly presents a security risk to the
users of Enso, please contact [security@enso.org](mailto:security@enso.org).**

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!

Even though GitHub search can sometimes be a bit hard to use, we'd appreciate if
you could
[search](https://github.com/enso-org/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/enso-org/ide/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
version of the IDE, as that will let us know if the bug is Operating System or
Architecture specific.

<br/>

## Development Environment

The project builds on macOS, Windows, and Linux. Cross-platform targets work
well on all of these platforms, however, macOS package will miss the right
application icon if built on Linux or Windows due to non-trivial icon generation
on these platforms. To develop the source code you will need the following
setup:

- **The Rust Toolchain**

  This project uses several features available only in the nightly Rust
  toolchain. Please use [the Rust toolchain installer](https://rustup.rs) to
  manage Rust toolchains. It will automatically download the toolchain needed to
  build the project.

  In addition, some custom CLI programs need to be installed manually:

  ```bash
  rustup toolchain install stable   # Stable toolchain required for the following tools.
  cargo +stable install wasm-pack   # Install the wasm-pack toolkit.
  cargo +stable install cargo-watch # To enable `./run wasm watch` utility
  ```

  Make sure that your `PATH` environment variable is set up correctly, so that
  the binaries installed by cargo
  ([typically to `$HOME/.cargo/bin`](https://doc.rust-lang.org/cargo/commands/cargo-install.html#description))
  can be run from the command line; verify this by running
  `wasm-pack --version`.

- **Node and Node Package Manager LTS**

  To build the web and desktop applications you will need
  [the latest LTS version of node and npm](https://nodejs.org/en/download). Even
  minor release changes are known to cause serious issues, thus **we provide
  support for the latest LTS version only. Please do not report build issues if
  you use other versions.** In case you run macOS or Linux the easiest way to
  set up the proper version is by installing the
  [Node Version Manager](https://github.com/nvm-sh/nvm) and running
  `nvm install --lts && nvm use --lts`.

- **(Optional) FlatBuffer compiler `flatc`**

  This dependency is needed only if you need to update files generated by the
  FlatBuffer from the Engine Services binary protocol description. Otherwise,
  relying on the generated files that are being stored in this repository is
  fine.

  `flatc` must be in the version _newer than 1.12_ due to
  [this bug](https://github.com/google/flatbuffers/issues/5055). As of writing
  this text there are no official releases with this issue fixed, however
  current binaries can be obtained from the project's CI
  [build artifacts](https://github.com/google/flatbuffers/actions?query=branch%3Amaster).
  `flatc` builds from 8 May 2020 onwards have been confirmed to work.

  After placing `flatc` in `PATH` you need to define the `ENSO_IDE_ENABLE_FLATC`
  environment variable to explicitly enable regeneration of the interface files.
  The `flatc` is run as part of `build.rs` script of the `enso-protocol package.

- **(Optional) The Latest version of `wasm-opt`**

  The version of `wasm-opt` that comes bundled with `wasm-pack` can be out of
  date and slow. We recommend to install a newer version from the
  [binaryen releases](https://github.com/WebAssembly/binaryen/releases), or
  [compile the newest version from scratch](https://github.com/WebAssembly/binaryen#building=).
  `wasm-pack` will pick up the locally installed version automatically and use
  it instead of the bundled one. Binaryen packages are also available through
  some system package managers (apt/pacman/brew), check whether the version
  there is newer than the bundled version of wasm-pack (which is true for all of
  them as of wasm-pack 0.10.2, which bundles version 90 which was released Dec
  2019).

<br/>

## Working with sources

Please be sure to carefully read the
[Rust style guide 1](contributing/style-guide.md) and the
[Rust style guide 2](https://enso.org/docs/developer/ide/contributing/style-guide.html)
before contributing to the codebase.

We do also use [`prettier`](https://prettier.io/) for the JavaScript and
Markdown files in our code base. If you have not installed it already you can do
so via `npm install prettier`. To use it manually via command line run
`prettier --write` to all JavaScript files in the project. Alternatively, there
are plugins for many IDEs available to do this for you.

### Repository Structure Overview

**Note**: Currently, the Enso repository is going through a process of
refactoring, and it is not finished yet: the Engine files are still not in the
`app/engine` where they ought to be, but in the root directory instead.

The root directory contains `Cargo.toml` and `build.sbt` files, allowing to open
all rust or scala code as a single project in your favorite IDE. There is also a
`run` and `run.cmd` scripts used for building and running the Enso IDE (see next
section for details).

The subdirectories of interests are:

- `app`: The actual products delivered in this repository:
  - `gui`: A rust crate compiled to a WASM library with all the logic of the GUI
    layer. The library is used by both the desktop application and the cloud
    environment. For further documentation see the documentation of the crate
    (at the top of the `src/lib.rs` file).
  - `ide-desktop`: The desktop version of the Enso IDE. Implemented as an
    electron application which spawns backend services, loads the WASM gui
    library and runs the main entry point.
  - `engine`: (In the future: see the note at the section beginning). The
    implementation of the language itself: CLI tools like compiler or
    interpreter, as well as the services used as a backend for the Enso IDE
    (Language Server and Project Manager).
- `lib`: All libraries not being the main components of our application. They
  are grouped by language. The most prominent are:
  - `rust/prelude`: A library containing the most popular utilities and imports.
    Should be imported in each rust module - see Contributing guidelines.
  - `rust/ensogl`: EnsoGL Framework for creating efficient GUI applications in
    WASM.
  - `rust/frp`: The library allows following the Functional Reactive Programming
    paradigm in rust.
- `build`: Build script that is wrapped by the `run` script.
- `integration-test`: A single crate with all integration tests of our
  applications.

Other directories are auto-generated `dist` and `target`, or (currently) are the
Engine files, which will be moved to `app/engine` soon.

### Development

As this is a multipart project with many complex dependencies, it is equipped
with a build script which both validates your working environment and takes care
of providing the most suitable compilation flags for a particular development
stage.

The build-script is invokable by invoking the following script from the working
copy root:

- `./run` in bash-compatible environments, like Linux or macOS;
- `.\run.cmd` on Windows.

For brevity, this guide will use `./run` form from here onwards.

In general, `./run` should also work on Windows ports of `bash` (like the ones
provided by `git` or MSYS2). These configurations are not tested though.

Run `./run --help` to learn about available commands and options. Some
subcommands allow passing additional arguments following `--` argument to the
underlying call. For example `./run ide build -- FLAG` will pass the `FLAG` flag
to `wasm-pack` (Rust WASM build tool). The most common options are presented
below:

- **Interactive mode** Run `./run ide watch` to start a local web-server and a
  source-file watch utility which will build the project on every change. Open
  `http://localhost:8080` (the port may vary and will be reported in the
  terminal if `8080` was already in use) to run the application, or
  `http://localhost:8080/?entry` to open example demo scenes list. Please
  remember to disable the cache in your browser during the development! By
  default, the script disables heavyweight optimizations to provide interactive
  development experience.
- **Production mode** In order to compile in a production mode (enable all
  optimizations, strip WASM debug symbols, minimize the output binaries, etc.),
  run `./run gui build`. To create platform-specific packages and installers use
  `./run ide build` instead. The final executables will be located at
  `dist/ide`.
- **Selective mode** In order to compile only part of the project, and thus
  drastically shorten the incremental compile time, you are advised to use the
  selective compilation mode by passing the `--crate-path` option to the `build`
  or `watch` command, e.g. `./run ide watch --crate-path ensogl/example` to
  compile only the renderer-related example scenes. Please note, that in order
  to run a scene in a web-browser, the scene has to be compiled and has to
  expose a public function with a name starting with `entry_point_`. Thus, if
  you compile only selected crate, you will have access only to the example
  scenes that were defined or re-exported by that crate. In particular, the
  `ide` crate exposes the `entry_point_ide` function, so you have to compile it
  to test your code in the Enso IDE.

### Using IDE as a library.

In case you want to use the IDE as a library, for example to embed it into
another website, you need to first build it using `./run gui build` and find the
necessary artifacts located at `dist/gui`. Especially, the
`dist/gui/assets/index.js` defines a function `window.enso.main(cfg)` which you
can use to run the IDE. Currently, the configuration argument can contain the
following options:

- `entry` - the entry point, one of predefined scenes. Set it to empty string to
  see the list of possible entry points.
- `project` - the project name to open after loading the IDE.

### Testing, Linting, and Validation

After changing the code it's always a good idea to lint and test the code. We
have prepared several scripts which maximally automate the process:

- **Size Validation** Use `./run wasm build` to check if the size of the final
  binary did not grew too much in comparison to the previous release. Watching
  the resulting binary size is one of the most important responsibility of each
  contributor in order to keep the project small and suitable for web-based
  usage. In case the size will exceed the limits:

  - If the PR does not include any new libraries, you are allowed to increase
    the limit by 10KB. In case the limit will be exceeded by more than 10KB,
    check which part of the code contribute to it, and talk about it with the
    code owner.
  - If the PR does include new libraries, you are allowed to increase the limit
    by 10KB, but you should also consider if it is possible to get the same
    results without using a new library (even by implementing few lines of code
    from the library in sources of the project).
  - If the PR does include new libraries, and the limit is exceeded by more than
    10KB, check which part of the code contributed to it, and talk about it with
    the code owner.
  - If the PR does include new libraries, and the limit is exceeded by more than
    50KB, it would probably not be merged. Research possible alternatives before
    talking with code owner about this case.

- **Testing** For the test suite to run you need a current version of Chrome
  installed. Use `./run wasm test` run both unit and web-based visual test.
- **Integration Tests** The integration tests are gathered in `integration-test`
  crate. You can run them with `./run ide integration-test` command. The script
  will spawn required Engine process.
  - To run une test suite add `-- --test <suite-name>` at end of command
    options. The `<suite-name>` is a name of the file in
    `integration-test/tests` directory without extension, for example
    `graph_editor`.
  - The integration test can create and leave new Enso projects. **Keep it in
    mind when running the script with your own backend (the `--external-backend`
    option)**. The Engine spawned by the script will use a dedicated workspace
    created in temporary directory, so the user workspace will not be affected.
- **Linting** Please be sure to fix all errors reported by `./run lint` before
  creating a pull request to this repository.

### Development Branches

The following branches are used to develop the product:

- **wip/[github_user_name]/[feature]** Feature branches. These are temporary
  branches used by the team to develop a particular feature.
- **develop** Contains the most recent changes to the product. After successful
  review, the feature branches are merged here. Each commit to this branch will
  result in a nightly build of the product accessible as CI artifacts.

- **unstable** Contains only those commits which can be considered unstable
  product releases. Each commit to this branch will result in an unstable
  release of the product and will be published on GitHub as a pre-release. The
  build version and build description will be automatically fetched from the
  newest `CHANGELOG.md` entry and will fail if the version will not be of the
  form `[major].[minor].[patch]-[sfx]`, where `[sfx]` is one of `alpha.[n]`,
  `beta.[n]`, or `rc.[n]`, where `[n]` is an unstable build number.

- **stable** Contains only those commits which can be considered stable product
  releases. Each commit to this branch will result in a stable release of the
  product and will be published on GitHub as a release. The build version and
  build description will be automatically fetched from the newest `CHANGELOG.md`
  entry and will fail if the version will not be of the form
  `[major].[minor].[patch]`.

### Forcing CI builds

By default, CI would not build artifacts from `wip` and `develop` branches in
order to save time and resources. If you want the artifacts to be build for your
PR, simply add `[ci build]` anywhere in the PR description.

### Skipping CHANGELOG.md change assertions

By default, CI would fail if the `CHANGELOG.md` file does not need to be
updated. However, sometimes there are PRs that does not change anything
significant in the final product. You can then simply add the 'CI: No changelog
needed' label to the PR to skip this assertion.

### Publishing Results

All new changes should be proposed in the form of Pull Requests (PRs) to this
repository. Each PR should contain changes to documentation and `CHANGELOG.md`
if applicable.

## Changelog

Please remember to update the `CHANGELOG.md` on every new bug fix or feature
implementation. Please note that `CHANGELOG.md` is used to establish the current
product version (the `run` script extracts it from the newest changelog entry).
Thus, be sure to always increase the newest version in the changelog after a
release, otherwise CI will fail. Please use the `docs/CHANGELOG_TEMPLATE.md` as
the template to create new changelog entries. Please note, that there is a
special syntax for defining features of the upcoming release. The newest
changelog entry can have a title "Next Release". In such a case, the build
version will be `0.0.0` and CI would fail when trying to publish it as a
release.