eqWAlizer

A type-checker for Erlang.

Using it with rebar3 projects

1. Use OTP 25

2. Download the elp binary for your system from https://github.com/WhatsApp/eqwalizer/releases

   On Mac you will probably get the following message when trying to run the executable the first time: "elp cannot be opened because the developer cannot be verified.". To solve this, go to Preferences > Security and Privacy and add an exception. Alternatively, you can build elp from source.

3. Add eqwalizer_support dependency and eqwalizer_rebar3 plugin to your rebar3 project definition (see below)

4. From the project directory run:

• elp eqwalize <module> to type-check a single module
• elp eqwalize-all to type-check all src modules in the project

Adding eqwalizer_support and eqwalizer_rebar3:

{deps, [
  {eqwalizer_support,
    {git_subdir,
        "https://github.com/whatsapp/eqwalizer.git",
        {branch, "main"},
        "eqwalizer_support"}}
]}.

{project_plugins, [
  {eqwalizer_rebar3,
    {git_subdir,
        "https://github.com/whatsapp/eqwalizer.git",
        {branch, "main"},
        "eqwalizer_rebar3"}}
]}.

Using it with non-rebar projects

1. Use OTP 25 (it will be detected automatically by eqWAlizer)
2. Download the elp binary for your system from https://github.com/WhatsApp/eqwalizer/releases
3. Write a project.json file describing your project, see below for the file structure. Ensure eqwalizer_support is added as a dependency, and that its ebin folder is reachable and populated with .beam files.
4. From the project directory, assuming your .json file is called project.json run:

• elp eqwalize <module> --project project.json to type-check a single module
• elp eqwalize-all --project project.json to type-check all src modules in the project

The .json file should be structured in this way:

{
  "apps": [app list],
  "deps": [app list],      // 3rd party dependencies (not type-checked), defaults to []
  "root": "path/to/root"   // Defaults to ""
}

where an app is a map structured as such:

{
  "name": "app_name",
  "dir": "path/to/app",                         // Relative to project root
  "src_dirs": ["path/to/src", ...],             // Relative to app dir, defaults to ["src"]
  "extra_src_dirs": ["path/to/extra_src", ...], // Relative to app dir, defaults to []
  "ebin": "path/to/ebin",                       // Relative to app dir, defaults to "ebin"
  "include_dirs": ["include", ...],             // Relative to app dir, defaults to []
  "macros": ["MACRO", ...],                     // Defaults to []
}

As an example, see the build_info.json file used to test mini-elp.

FAQ

Please refer to the FAQ document for answers to some common questions, including:

• What's the difference between eqWAlizer and Dialyzer?
• Why not extend Dialyzer, rather than creating a new tool?
• What about Elixir?

Where can I learn more about eqWAlizer, its technical principles, its relation to dialyzer and elixir support feasibility?

here.

License

eqWAlizer is Apache licensed.