Setting Up Julia LSP for Neovim

Date: August 31 2022

Summary: An explanation of how to setup the Julia LSP for Neovim

Keywords: ##summary #neovim #julia #programming #archive

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1. General Guide
How To Cite
References
Discussion:

General Guide

This is from Fredrik Ekre at the Julia Discourse with some minimal changes and notes from me:

LanguageServer is somewhat slow to start so it is very useful to use a custom sysimage using PackageCompiler to reduce this time. On my machine I get the first response after 20+ seconds, but with a custom sysimage I can execute LS commands instantaneously.

Here is my setup:

Install Mason.nvim or nvim-lspconfig and install julials (it may also be called something like Julia Language Server Protocol).
Modify init.vim or init.lua to use a custom Julia executable (if it exists):

require'lspconfig'.julials.setup{
    on_new_config = function(new_config, _)
        local julia = vim.fn.expand("~/.julia/environments/nvim-lspconfig/bin/julia")
        if require'lspconfig'.util.path.is_file(julia) then
	    vim.notify("Hello!")
            new_config.cmd[1] = julia
        end
    end
}

(OPTIONAL) If you use Packer to manage your vim setup, run PackerCompile.

NOTE: If you notice, there is a small line named vim.notify("Hello!"). This is to test that julials is engaged when accessing a Julia file - you can check that it is engaged by writing :messages in vim. You should see "Hello!" appear. This line can then safely be removed.

Create the nvim-lspconfig Julia environment by running the following in your shell:

julia --project=~/.julia/environments/nvim-lspconfig -e 'using Pkg; Pkg.add("LanguageServer")'

And then navigate to the directory at ~.julia/environment/nvim-lspconfig.

Copy the following makefile (courtesy of Fredrik Ekre) the nvim-lspconfig directory with the name makefile:

# MIT License. Copyright (c) 2021 Fredrik Ekre
#
# This Makefile can be used to build a custom Julia system image for LanguageServer.jl to
# use with neovims built in LSP support. An up-to date version of this Makefile can be found
# at https://github.com/fredrikekre/.dotfiles/blob/master/.julia/environments/nvim-lspconfig/Makefile
#
# Usage instructions:
#
#   1. Update the neovim configuration to use a custom julia executable. If you use
#      nvim-lspconfig (recommended) you can modify the setup call to the following:
#
#          require("lspconfig").julials.setup({
#              on_new_config = function(new_config, _)
#                  local julia = vim.fn.expand("~/.julia/environments/nvim-lspconfig/bin/julia")
#                  if require("lspconfig").util.path.is_file(julia) then
#                      new_config.cmd[1] = julia
#                  end
#              end,
#              -- ...
#          })
#
#   2. Place this Makefile in ~/.julia/environments/nvim-lspconfig (create the directory if
#      it doesn't already exist).
#
#   3. Change directory to ~/.julia/environments/nvim-lspconfig and run `make`. This will
#      start up neovim in a custom project with a julia process that recods compiler
#      statements. Follow the instructions in the opened source file, and then exit neovim.
#
#   4. Upon exiting neovim PackageCompiler.jl will compile a custom system image which will
#      automatically be used whenever you work on Julia projects in neovim.
#
# Update instructions:
#
#  To update the system image (e.g. when upgrading Julia or upgrading LanguageServer.jl or
#  it's dependencies) run the following commands from the
#  ~/.julia/environments/nvim-lspconfig directory:
#
#      julia --project=. -e 'using Pkg; Pkg.update()'
#      make

JULIA=$(shell which julia)
JULIA_PROJECT=
SRCDIR:=$(shell dirname $(abspath $(firstword $(MAKEFILE_LIST))))
ifeq ($(shell uname -s),Linux)
	SYSIMAGE=languageserver.so
else
	SYSIMAGE=languageserver.dylib
endif

default: $(SYSIMAGE)

$(SYSIMAGE): Manifest.toml packagecompiler/Manifest.toml packagecompiler/precompile_statements.jl
	JULIA_LOAD_PATH=${PWD}:${PWD}/packagecompiler:@stdlib ${JULIA} -e 'using PackageCompiler; PackageCompiler.create_sysimage(:LanguageServer, sysimage_path="$(SYSIMAGE)", precompile_statements_file="packagecompiler/precompile_statements.jl")'

Manifest.toml: Project.toml
	JULIA_LOAD_PATH=${PWD}/Project.toml:@stdlib ${JULIA} -e 'using Pkg; Pkg.instantiate()'

Project.toml:
	JULIA_LOAD_PATH=${PWD}/Project.toml:@stdlib ${JULIA} -e 'using Pkg; Pkg.add("LanguageServer")'

packagecompiler/Manifest.toml: packagecompiler/Project.toml
	JULIA_LOAD_PATH=${PWD}/packagecompiler/Project.toml:@stdlib ${JULIA} -e 'using Pkg; Pkg.instantiate()'

packagecompiler/Project.toml:
	mkdir -p packagecompiler
	JULIA_LOAD_PATH=${PWD}/packagecompiler/Project.toml:@stdlib ${JULIA} -e 'using Pkg; Pkg.add("PackageCompiler")'

packagecompiler/precompile_statements.jl: Manifest.toml bin/julia
	TMPDIR=$(shell mktemp -d) && \
	cd $${TMPDIR} && \
	JULIA_LOAD_PATH=: ${JULIA} -e 'using Pkg; Pkg.generate("Example")' 2> /dev/null && \
	cd Example && \
	JULIA_LOAD_PATH=$${PWD}:@stdlib ${JULIA} -e 'using Pkg; Pkg.add(["JSON", "fzf_jll", "Random", "Zlib_jll"])' 2> /dev/null && \
	JULIA_LOAD_PATH=$${PWD}:@stdlib ${JULIA} -e 'using Pkg; Pkg.precompile()' 2> /dev/null && \
	echo "$$PACKAGE_CONTENT" > src/Example.jl && \
	JULIA_TRACE_COMPILE=1 nvim src/Example.jl && \ # NOTE: You may need to check that neovim is correctly on your path
	rm -rf $${TMPDIR}

bin/julia:
	mkdir -p bin
	echo "$$JULIA_SHIM" > $@
	chmod +x $@

clean:
	rm -rf $(SYSIMAGE) packagecompiler bin

.PHONY: clean default

export JULIA_SHIM
define JULIA_SHIM
#!/bin/bash
JULIA=${JULIA}
if [[ $${JULIA_TRACE_COMPILE} = "1" ]]; then
    exec $${JULIA} --trace-compile=${PWD}/packagecompiler/precompile_statements.jl "$$@"
elif [[ -f ${PWD}/$(SYSIMAGE) ]]; then
    exec $${JULIA} --sysimage=${PWD}/$(SYSIMAGE) "$$@"
else
    exec $${JULIA} "$$@"
fi
endef

export PACKAGE_CONTENT
define PACKAGE_CONTENT
# This file is opened in neovim with a LanguageServer.jl process that records Julia
# compilation statements for creating a custom sysimage.
#
# This file has a bunch of linter errors which will exercise the linter and record
# statements for that. When the diagnostic messages corresponding to those errors show up in
# the buffer the language server should be ready to accept other commands (note: this may
# take a while -- be patient). Here are some suggestions for various LSP functionality that
# can be exercised (your regular keybindings should work):
#
#  - :lua vim.lsp.buf.hover()
#  - :lua vim.lsp.buf.definition()
#  - :lua vim.lsp.buf.references()
#  - :lua vim.lsp.buf.rename()
#  - :lua vim.lsp.buf.formatting()
#  - :lua vim.lsp.buf.formatting_sync()
#  - :lua vim.lsp.buf.code_action()
#  - Tab completion (if you have set this up using LSP)
#  - ...
#
# When you are finished, simply exit neovim and PackageCompiler.jl will use all the recorded
# statements to create a custom sysimage. This sysimage will be used for the language server
# process in the future, and should result in almost instant response.

module Example

import JSON
import fzf_jll
using Random
using Zlib_jll

function hello(who, notused)
    println("hello", who)
    shuffle([1, 2, 3])
   shoffle([1, 2, 3])
    fzzf = fzf_jll.fzzf()
    fzf = fzf_jll.fzf(1)
    JSON.print(stdout, Dict("hello" => [1, 2, 3]), 2, 123)
    JSON.print(stdout, Dict("hello" => [1, 2, 3]))
    hi(who)
    return Zlib_jll.libz
end

function world(s)
    if s == nothing
      hello(s)
  else
      hello(s)
  end
    x = [1, 2, 3]
    for i in 1:length(x)
        println(x[i])
    end
end

end # module
endef

Run make. This will set up a dummy project and launch nvim with julia recording everything that is compiled. Wait until the LanguageServer responds (there are a bunch of things in this dummy project that will result in warnings) and then run some LanguageServer commands, for example ::lua vim.lsp.buf.hover() to fetch documentation).
Quit vim.
PackageCompiler will now build a custom languageserver.so sysimage.
Enjoy the Julia LSP!

Setting Up Julia LSP for Neovim

Bibliography

Table of Contents

General Guide

How To Cite

References

Discussion: