IntelliJ

Setup

WARNING: The current version of the IntelliJ LSP plugin (1.6.1) is quite limited, so not all of the Erlang Language Server capabilities are available in IntelliJ.

First of all, ensure you have the LSP Support plugin installed. If you don't, you can simply navigate to:

Preferences > Plugins > Browse Repositories

Search for "LSP Support" and install the respective plugin.

Restart IntelliJ, then navigate to:

Preferences > Languages and Frameworks > Language Server Protocol > Server Definitions

There you can instruct IntelliJ on how to start the server. Select Raw Command, set erl;hrl as the extension, then add as the command:

/ABSOLUTE/PATH/TO/erlang_ls/_build/default/bin/erlang_ls --transport stdio

Ensure you use an absolute path. The plugin does not seem to understand the ~ symbol. For the above command to work, IntelliJ requires the PATH variable to be correctly configured to include Erlang 20+. To circumvent this issues on Mac OS, the best way is to start IntelliJ from the terminal (i.e. via the idea command) and not via Spotlight.

To visualize documentation and type specs while hovering a function, ensure the Show quick documentation on mouse move option is enabled in your IntelliJ preferences:

Preferences > Editor > General

There, you can also set a delay in milliseconds.

For more information about how to configure the IntelliJ LSP Client, please refer to the project GitHub page.

Troubleshooting

In some cases, the IntelliJ LSP client may not be able to connect to the server. In such cases, the first step is to enable logging:

Preferences > Languages and Frameworks > Language Server Protocol

Check the Log servers communications check-box there.

After restarting IntelliJ, you will notice an extra lsp directory created inside your Erlang project. This directory contains the error and output logs, which should give you a hint about what is going on.

An alternative source of information is represented by the IntelliJ logs:

Help > Show Logs