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Emacs

The ELP project can be used as a language server in the Emacs text editor via the eglot or lsp-mode LSP clients.

Eglot​

Eglot is part of Emacs core since Emacs 29. For earlier versions it can be installed with the eglot package.

Configuration​

(use-package eglot

  :config
  ;; Remove default LSP server
  (setopt eglot-server-programs
          (assq-delete-all 'erlang-mode eglot-server-programs))

  ;; Enable ELP
  (add-to-list 'eglot-server-programs
               '(erlang-mode . ("elp" "server"))

Refer to the manual for additional configuration options.

lsp-mode​

Install the lsp-mode package, which is a generic Emacs client for LSP servers. You can follow these instructions to install it.

Configuration​

Add the following to your emacs .emacs file or equivalent.

(use-package lsp-mode

  :config
  ;; Enable LSP automatically for Erlang files
  (add-hook 'erlang-mode-hook #'lsp)

  ;; ELP, added as priority 0 (> -1) so takes priority over the built-in one
  (lsp-register-client
   (make-lsp-client :new-connection (lsp-stdio-connection '("elp" "server"))
                    :major-modes '(erlang-mode)
                    :priority 0
                    :server-id 'erlang-language-platform))
  )

For a list of available configuration option, please refer to this page and to the lsp-mode settings documentation.

Troubleshooting​

The following servers support current file but do not have automatic installation​

Ensure that the elp executable is available in your PATH via Emacs. A workaround is:

;; Ensure your Emacs environment looks like your user's shell one
(package-require 'exec-path-from-shell)
(exec-path-from-shell-initialize)