Use the PYLS python LSP with ALE on Neovim

Question

I installed NeoVim and dense-analysis/ale plugin with vim-plug.

All of those seems to be installed, as the commands starting with :ALE autocomplete in NeoVim.

Then I tried to install PYLS via

python3 -m pip install --user python-language-server

and enabled it in my init.vim file that you can read here :

# File .config/nvim/init.vim
call plug#begin('~/.config/nvim/plugged')
Plug 'dense-analysis/ale'
let g:ale_linters = {'python': ['pyls']}
let g:ale_fixers = {'python': ['black']}
let g:ale_lint_on_text_changed = 'never'
let g:ale_lint_on_insert_leave = 0
let g:ale_lint_on_enter = 0
let g:ale_completion_enabled = 1
call plug#end()

" Display
set number " show the line numbers
set cursorline " underline the current line
colorscheme koehler " use my preferred palette

" Syntax highlighting
syntax on

" Set tabs to have 4 spaces
set tabstop=4 " nb of spaces in a tab
set softtabstop=4
set shiftwidth=4 " nb of spaces when using << or >>
set expandtab " use spaces when pressing <tab>

" Input
set mouse=a

" Output
set fileformat=unix
set encoding=utf-8

The problem is : commands like ":ALEGoToDefinition" or ":ALEFindReferences" don't work.

I saw that PYLS need Jedi to provide those, so I installed Jedi too.

python3 -m pip install --user jedi

But there's no change.

Here's my :ALEInfo content :

:ALEInfo...
 Current Filetype: python
Available Linters: ['bandit', 'flake8', 'mypy', 'prospector', 'pycodestyle', 'pydocstyle', 'pyflakes', 'pylama', 'pylint', 'pyls', 'pyre', 'vulture']
 Current Filetype: python
Available Linters: ['bandit', 'flake8', 'mypy', 'prospector', 'pycodestyle', 'pydocstyle', 'pyflakes', 'pylama', 'pylint', 'pyls', 'pyre', 'vulture']
  Enabled Linters: ['pyls']
 Suggested Fixers:
  'add_blank_lines_for_python_control_statements' - Add blank lines before control statements.
  'autopep8' - Fix PEP8 issues with autopep8.
  'black' - Fix PEP8 issues with black.
  'isort' - Sort Python imports with isort.
  'remove_trailing_lines' - Remove all blank lines at the end of a file.
  'reorder-python-imports' - Sort Python imports with reorder-python-imports.
  'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
  'yapf' - Fix Python files with yapf.
 Linter Variables:
let g:ale_python_auto_pipenv = 0
let g:ale_python_pyls_auto_pipenv = 0
let g:ale_python_pyls_config = {}
let g:ale_python_pyls_executable = 'pyls'
let g:ale_python_pyls_use_global = 0
 Global Variables:
let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = v:null
let g:ale_command_wrapper = v:null
let g:ale_completion_delay = 100
let g:ale_completion_enabled = 1
let g:ale_completion_max_suggestions = 50
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = v:null
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {'python': ['black']}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = v:null
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 0
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 0
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'never'
let g:ale_linter_aliases = {}
let g:ale_linters = {'python': ['pyls']}
let g:ale_linters_explicit = 0
let g:ale_list_vertical = v:null
let g:ale_list_window_size = v:null
let g:ale_loclist_msg_format = v:null
let g:ale_lsp_root = {}
let g:ale_max_buffer_history_size = v:null
let g:ale_max_signs = v:null
let g:ale_maximum_file_size = v:null
let g:ale_open_list = v:null
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_set_balloons = 0
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = v:null
let g:ale_sign_error = v:null
let g:ale_sign_info = v:null
let g:ale_sign_offset = v:null
let g:ale_sign_style_error = v:null
let g:ale_sign_style_warning = v:null
let g:ale_sign_warning = v:null
let g:ale_statusline_format = v:null
let g:ale_type_map = v:null
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
  Command History:

Press ENTER or type command to continue

Did I forget some steps ? Thanks you

Answer 1

OP, are you using a Macbook? Here's what worked for me to get :ALEGoToDefinition working in my Python 3.8 projects using Vim 8.2.330 on both my Macbook and my Linux Mint 19.3 machine:

1. pipx install 'python-language-server[rope]'

installed package python-language-server 0.36.2, Python 3.10.0
  These apps are now globally available
    - pyls

2. Now if I open up any Python file in Vim and do :ALEInfo it shows pylsp as an available linter on my Macbook, but it shows up as pyls on my Linux Mint 19.3 machine. Interesting.

3. Macbook: Update ~/.vimrc to include pylsp as a linter for Python:

let g:ale_linters = {
\   'python': ['flake8', 'mypy', 'pylsp'],
\}

4. Macbook: It still didn't work because the default executable name of pylsp is incorrect. So I went back into my ~/.vimrc and fixed that variable:

let g:ale_python_pylsp_executable = 'pyls'

5. Now the Macbook is working! On the Linux machine, the name was correct from the beginning, so all I needed to do was add pyls as a linter and everything worked (no need to override the executable variable):

let g:ale_linters = {
\   'python': ['flake8', 'mypy', 'pyls'],
\}

Answer 2

python-language-server requires registration. (See Servers-Python)

Here are two options to do this:

1. Install vim-lsp
2. Register the python-language-server in .vimrc

if executable('pyls')
    au User lsp_setup call lsp#register_server({
        \ 'name': 'pyls',
        \ 'cmd': {server_info->['pyls']},
        \ 'allowlist': ['python'],
        \ })
endif