coc-metals

coc-metals

coc.nvim extension for Metals, the Scala Language Server.

This extension is meant to mimic the functionality provided by the metals-vscode extension.

Requirements

• coc.nvim
• Java 8 or 11 provided by OpenJDK or Oracle. Eclipse OpenJ9 is not supported, please make sure the JAVA_HOME environment variable points to a valid Java 8 or 11 installation.

Quick Start

:CocInstall coc-metals

Following the installation of the extension, you simply need to open the directory that contains your scala project. Then upon entering your build.sbt or any scala file, a few checks will automatically happen:

1. Ensures that you have a valid Java installation
2. Ensures you have the most up to date Metals version listed in your config, or it will default to the latest stable release
3. If Metals is not available, it will download Metals

After the download, Metals will automatically start. At this point you should see the prompt to import your build.

coc.nvim mappings

There are purposefully no default mappings for coc.nvim, so you'll want to ensure you have the following added to your .vimrc. You are then able to customize it as you choose.

" ~/.vimrc
" Configuration for coc.nvim

" Smaller updatetime for CursorHold & CursorHoldI
set updatetime=300

" don't give |ins-completion-menu| messages.
set shortmess+=c

" always show signcolumns
set signcolumn=yes

" Some server have issues with backup files, see #649
set nobackup
set nowritebackup

" Better display for messages
set cmdheight=2

" Use <c-space> for trigger completion.
inoremap <silent><expr> <c-space> coc#refresh()

" Use <cr> for confirm completion, `<C-g>u` means break undo chain at current position.
" Coc only does snippet and additional edit on confirm.
inoremap <expr> <cr> pumvisible() ? "\<C-y>" : "\<C-g>u\<CR>"

" Use `[c` and `]c` for navigate diagnostics
nmap <silent> [c <Plug>(coc-diagnostic-prev)
nmap <silent> ]c <Plug>(coc-diagnostic-next)

" Remap keys for gotos
nmap <silent> gd <Plug>(coc-definition)
nmap <silent> gy <Plug>(coc-type-definition)
nmap <silent> gi <Plug>(coc-implementation)
nmap <silent> gr <Plug>(coc-references)

" Remap for do codeAction of current line
nmap <leader>ac <Plug>(coc-codeaction)

" Remap for do action format
nnoremap <silent> F :call CocAction('format')<CR>

" Use K for show documentation in preview window
nnoremap <silent> K :call <SID>show_documentation()<CR>

function! s:show_documentation()
  if &filetype == 'vim'
    execute 'h '.expand('<cword>')
  else
    call CocAction('doHover')
  endif
endfunction

" Highlight symbol under cursor on CursorHold
autocmd CursorHold * silent call CocActionAsync('highlight')

" Remap for rename current word
nmap <leader>rn <Plug>(coc-rename)

" Show all diagnostics
nnoremap <silent> <space>a  :<C-u>CocList diagnostics<cr>
" Find symbol of current document
nnoremap <silent> <space>o  :<C-u>CocList outline<cr>
" Search workspace symbols
nnoremap <silent> <space>s  :<C-u>CocList -I symbols<cr>
" Do default action for next item.
nnoremap <silent> <space>j  :<C-u>CocNext<CR>
" Do default action for previous item.
nnoremap <silent> <space>k  :<C-u>CocPrev<CR>
" Resume latest coc list
nnoremap <silent> <space>p  :<C-u>CocListResume<CR>

" Notify coc.nvim that <enter> has been pressed.
" Currently used for the formatOnType feature.
inoremap <silent><expr> <cr> pumvisible() ? coc#_select_confirm()
      \: "\<C-g>u\<CR>\<c-r>=coc#on_enter()\<CR>"

Configuration

The following configuration options are currently available. The easiest way to set these configurations is to enter :CocConfig or :CocLocalConfig to set your global or local configuration settings respectively. If you'd like to get autocompletion help for the configuration values you can install coc-json.

Configuration Option	Description
metals.serverVersion	The version of the Metals server artifact. Requires reloading the window.
metals.serverProperties	Optional list of properties to pass along to the Metals server. By default, the environment variable JAVA_OPTS and .jvmopts file are respected.
metals.javaHome	Optional path to the Java home directory. Requires reloading the window.\n\nDefaults to the most recent Java 8 version computed by the locate-java-home npm package.
metals.sbtScript	Optional absolute path to an sbt executable to use for running sbt bloopInstall. By default, Metals uses java -jar sbt-launch.jar with an embedded launcher while respecting .jvmopts and .sbtopts.\n\nUpdate this setting if your sbt script requires more customizations like using environment variables.
metals.millScript	Optional absolute path to a mill executable to use for running mill mill.contrib.Bloop/install. By default, Metals uses an embedded millw script while respecting .mill-version file. Update this setting if your mill script requires more customizations.
metals.mavenScript	Optional absolute path to a mvn executable to use for running mvn ch.epfl.scala:maven-bloop_2.10:<bloop_version>:bloopInstall. By default, Metals uses an embedded mvnw script. Update this setting if your mvn script requires more customizations.
metals.gradleScript	Optional absolute path to a gradle executable to use for running gradle bloopInstall. By default, Metals uses an embedded gradlew script. Update this setting if your gradle script requires more customizations.
metals.scalafmtConfigPath	Optional custom path to the .scalafmt.conf file. Should be relative to the workspace root directory and use forward slashes / for file separators (even on Windows).
metals.customRepositories	Optional list of custom resolvers passed to Coursier when fetching metals dependencies.\n\nFor documentation on accepted values see the Coursier documentation. The extension will pass these to Coursier using the COURSIER_REPOSITORIES environment variable after joining the custom repositories with a pipe character (

Available Commands

In order to either view or execute a commnad, enter :CocCommand which will bring up a fuzzy finder where you can search for any available coc.nvim or Metals command. You can also use the <space> c shortcut if you copied the above coc mappings.

The following command are currently available:

• metals.restartServer
• metals.build-import
• metals.build-connect
• metals.sources-scan
• metals.compile-cascade
• metals.compile-cancel
• metals.doctor-run

Troubleshooting

Again, this is currently a work in progress and many things are still being implemented. For the time being it's still recommend to manually set up Metals with coc.nvim. You can find instructions on the setup here on the Metals website.

If you have any questions or issues with Metals, please submit an issue in this repo if it pertains to the extension or in the main Metals issue repo if it relates to Metals in general. If you have any feature requests, we also have a feature request issue repo.