lang/julia: improve lsp support (#4012)

* lang/julia: include lsp-julia w/o language server

Use nonrecursive clone to get lsp-julia without bundled
LanguageServer.jl (plus dependencies) and include instructions in the
README on how to install the language server (bundled or otherwise).

* lang/julia: add checks for julia +lsp in doctor

Add two checks, both only for when the +lsp feature is enabled:
- Check if (:tools lsp) is selected
- Check if LanguageServer.jl is installed

* lang/julia: indicate SymbolServer.jl as dependency

It is itself a dependency of LanguageServer.jl, but it's necessary to
add it separately in order to do `using SymbolServer`.

* tools/lsp: add julia language server to list

* lang/julia: add eglot support using eglot-jl

Forcing eglot-jl to not install its own LanguageServer.jl is a bit of a
hack though.

* lang/julia: make timeout increase buffer-local

Suggestion by @benneti to use `setq-local` instead of `setq` to prevent
a timeout increase in non-Julia eglot buffers.

* Fix issues

Co-authored-by: Henrik Lissner <henrik@lissner.net>

docs/modules.org

@@ -118,7 +118,7 @@ Modules that bring support for a language or group of languages to Emacs.
 + java =+meghanada +eclim +lsp= - TODO
 + [[file:../modules/lang/javascript/README.org][javascript]] =+lsp= - JavaScript, TypeScript, and CoffeeScript support
 + [[file:../modules/lang/json/README.org][json]] =+lsp= - TODO
-+ julia =+lsp= - TODO
++ [[file:../modules/lang/julia/README.org][julia]] =+lsp= - TODO
 + kotlin =+lsp+= - TODO
 + [[file:../modules/lang/latex/README.org][latex]] =+latexmk +cdlatex +fold +lsp= - TODO
 + lean - TODO

modules/lang/julia/README.org

@@ -1,6 +1,6 @@
 #+TITLE:   lang/julia
 #+DATE:    April 8, 2020
-#+SINCE:   {replace with next tagged release version}
+#+SINCE:   v1.3
 #+STARTUP: inlineimages nofold
 
 * Table of Contents :TOC_3:noexport:
@@ -9,47 +9,97 @@
   - [[#plugins][Plugins]]
 - [[#prerequisites][Prerequisites]]
   - [[#language-server][Language Server]]
+    - [[#lsp-julia][~lsp-julia~]]
+    - [[#eglot-jl][~eglot-jl~]]
 - [[#features][Features]]
   - [[#language-server-1][Language Server]]
 - [[#configuration][Configuration]]
+  - [[#change-the-default-environment-for-the-julia-language-server][Change the default environment for the Julia language server]]
 
 * Description
-Adds Julia support to Doom Emacs
+This module adds support for [[https://julialang.org/][the Julia language]] to Doom Emacs.
 
 + Syntax highlighting and latex symbols from ~julia-mode~
 + REPL integration from ~julia-repl~
 + Code completion and syntax checking, requires ~:tools lsp~ and ~+lsp~
 
 ** Module Flags
-+ =+lsp= Language Server Protocol support
++ =+lsp= Enable LSP server support.
+
 ** Plugins
 + [[https://github.com/tpapp/julia-repl][julia-mode]]
 + [[https://github.com/JuliaEditorSupport/julia-emacs/][julia-repl]]
 + =+lsp= and =:tools lsp=
-  + [[https://github.com/non-jedi/lsp-julia][lsp-julia]]*
+  + [[https://github.com/non-jedi/lsp-julia][lsp-julia]]
   + [[https://github.com/emacs-lsp/lsp-mode][lsp]]
++ =+lsp= and =:tools lsp +eglot=
+  + [[https://github.com/non-jedi/eglot-jl][eglot-jl]]
+  + [[https://github.com/joaotavora/eglot][eglot]]
 
 * Prerequisites
-This module has no direct prerequisites.
+This module requires =julia= and an language server if =+lsp= is enabled.
 
 ** Language Server
+~+lsp~ requires ~LanguageServer.jl~ and ~SymbolServer.jl~. The =lsp-julia= and
+=eglot-jl= packages both come bundled with their own versions of these servers,
+which is used by default. If you're happy with that, no further configuration is
+necessary.
 
-~+lsp~ requires the a manual installation of ~lsp-julia~ as it comes with a
+However, to use your own installation you will need to install then configure
-packaged version of ~LanguageServer.jl~ and its dependencies.
+them. To install them, execute these commands in a Julia REPL:
+
+#+BEGIN_SRC julia
+using Pkg
+Pkg.add("LanguageServer")
+Pkg.add("SymbolServer")
+#+END_SRC
+
+Then configure =lsp-julia= or =eglot-jl= depending on whether you have enabled
+=:tools lsp= or =:tools (lsp +eglot)=, respectively:
+
+*** ~lsp-julia~
+To instruct =lsp-julia= not to use the built-in package:
 
 #+BEGIN_SRC elisp
-;; ~/.doom.d/packages.el
+;; ~/.doom.d/config.el
-(package! lsp-julia :recipe (:host github :repo "non-jedi/lsp-julia"))
+(setq lsp-julia-package-dir nil)
+#+END_SRC
+
+To find your installation of ~LanguageServer.jl~, ~eglot-jl~ needs to know the
+environment in which it is installed. This is set to v1.0 by default as it is
+the current LTS:
+
+#+BEGIN_SRC elisp
+(setq lsp-julia-default-environment "~/.julia/environments/v1.0")
+#+END_SRC
+
+*** ~eglot-jl~
+To find your installation of ~LanguageServer.jl~, ~eglot-jl~ must know the
+environment in which it is installed. This is set to v1.0 by default as it is
+the current LTS:
+
+#+BEGIN_SRC elisp
+;; ~/.doom.d/config.el
+(setq eglot-jl-language-server-project "~/.julia/environments/v1.0")
+#+END_SRC
+
+But to let ~eglot-jl~ use the environment bundled with it, set it to
+~eglot-jl-base~ instead:
+
+#+BEGIN_SRC elisp
+;; ~/.doom.d/config.el
+(after! eglot-jl
+  (setq eglot-jl-language-server-project eglot-jl-base))
 #+END_SRC
 
 * Features
-  # An in-depth list of features, how to use them, and their dependencies.
 ** Language Server
-   ~+lsp~ adds code completion, syntax checking, formatting and other ~lsp-mode~
+~+lsp~ adds code completion, syntax checking, formatting and other ~lsp-mode~ or
-   features. This requires a manual installation of ~lsp-julia~ as it bundles
+~eglot~ features. It requires ~LanguageServer.jl~, the installation of which is
-   ~LanguageServer.jl~ and its dependencies.
+described above.
 
 * Configuration
+** Change the default environment for the Julia language server
 ~lsp-julia~ requires a variable be set for the Julia environment. This is set to
 v1.0 by default as it is the current LTS.
 
@@ -57,11 +107,3 @@ v1.0 by default as it is the current LTS.
 ;; ~/.doom.d/config.el
 (setq lsp-julia-default-environment "~/.julia/environments/v1.0")
 #+END_SRC
-
-If you would like to use your own installation of ~LanguageServer.jl~, put the
-following in your personal ~config.el~.
-
-#+BEGIN_SRC elisp
-;; ~/.doom.d/config.el
-(setq lsp-julia-package-dir nil)
-#+END_SRC

modules/lang/julia/config.el

@@ -65,10 +65,26 @@
     (term-set-escape-char ?\C-c)))
 
 
+(when (featurep! +lsp)
+  (add-hook 'julia-mode-local-vars-hook #'lsp!))
+
+
 (use-package! lsp-julia
   :when (featurep! +lsp)
+  :unless (featurep! :tools lsp +eglot)
   :after lsp-mode
   :preface
-  (setq lsp-julia-default-environment "~/.julia/environments/v1.0")
+  (setq lsp-julia-default-environment "~/.julia/environments/v1.0"))
-  (when (featurep! +lsp)
+
-    (add-hook 'julia-mode-local-vars-hook #'lsp!)))
+
+(use-package! eglot-jl
+  :when (featurep! +lsp)
+  :when (featurep! :tools lsp +eglot)
+  :after eglot
+  :preface
+  ;; Prevent auto-install of LanguageServer.jl
+  (setq eglot-jl-language-server-project "~/.julia/environments/v1.0")
+  :init
+  ;; Prevent timeout while installing LanguageServer.jl
+  (setq-hook! 'julia-mode-hook eglot-connect-timeout (max eglot-connect-timeout 60))
+  :config (eglot-jl-init))

modules/lang/julia/doctor.el

@@ -0,0 +1,19 @@
+;;; lang/julia/doctor.el -*- lexical-binding: t; -*-
+
+(assert! (or (not (featurep! +lsp))
+             (featurep! :tools lsp))
+         "This module requires (:tools lsp)")
+
+(when (featurep! +lsp)
+  (let ((args
+         (cond ((require 'eglot-jl nil t)
+                `(,eglot-jl-julia-command
+                  ,(concat "--project=" eglot-jl-language-server-project)
+                  ,@eglot-jl-julia-flags
+                  "-e" "empty!(LOAD_PATH); push!(LOAD_PATH, \"@\"); using LanguageServer, SymbolServer"))
+               ((require 'lsp-julia nil t)
+                `(,lsp-julia-command
+                  ,@lsp-julia-flags
+                  "-e" "using LanguageServer, SymbolServer")))))
+    (unless (zerop (car (apply #'doom-call-process args)))
+      (warn! "Couldn't find LanguageServer.jl and/or SymbolServer.jl"))))

modules/lang/julia/packages.el

@@ -3,3 +3,8 @@
 
 (package! julia-mode :pin "8ea90c7927f6d87a291cfb0216f34dacf43c722e")
 (package! julia-repl :pin "7ce38a9caf2a9c105afe66f464a2f30e816d69f3")
+
+(when (featurep! +lsp)
+  (if (featurep! :tools lsp +eglot)
+      (package! eglot-jl :pin "84cff9d6ef1643f3eac6c9d620cc1e380a9847d9")
+    (package! lsp-julia :recipe (:nonrecursive t) :pin "c523c250c4bd2777203101ab417e9b7312472f46")))

modules/tools/lsp/README.org

@@ -45,6 +45,7 @@ As of this writing, this is the state of LSP support in Doom Emacs:
 | [[../../lang/haskell/README.org][:lang haskell]]    | haskell-mode                                            | haskell-language-server                                       |
 | [[../../lang/java/README.org][:lang java]]       | java-mode                                               | lsp-java                                                      |
 | [[../../lang/javascript/README.org][:lang javascript]] | js2-mode, rjsx-mode, typescript-mode                    | typescript-language-server                                    |
+| [[../../lang/julia/README.org][:lang julia]]      | julia-mode                                              | LanguageServer.jl                                             |
 | [[../../lang/ocaml/README.org][:lang ocaml]]      | tuareg-mode                                             | ocaml-language-server                                         |
 | [[../../lang/php/README.org][:lang php]]        | php-mode                                                | php-language-server                                           |
 | [[../../lang/python/README.org][:lang python]]     | python-mode                                             | lsp-python-ms                                                 |