languageserver is an implementation of the Microsoft's Language Server Protocol for the language of R.

It is released on CRAN and can be easily installed by

install.packages("languageserver")

The development version of languageserver could be installed by running the following in R:

# install.packages("devtools")
devtools::install_github("REditorSupport/languageserver")

These editors are supported by installing the corresponding package.

• VSCode: vscode-r-lsp

• Atom: atom-ide-r

• Sublime Text: R-IDE

• Vim/NeoVim: LanguageClient-neovim with settings

  let g:LanguageClient_serverCommands = {
      \ 'r': ['R', '--slave', '-e', 'languageserver::run()'],
      \ }

  or use coc-r-lsp with coc.nvim

• Emacs: lsp-mode

• JupyterLab: jupyterlab-lsp

languageserver is still under active development, the following services have been implemented:

• textDocumentSync
• publishDiagnostics
• hoverProvider
• completionProvider
• completionItemResolve
• signatureHelpProvider
• definitionProvider
• referencesProvider
• documentHighlightProvider
• documentSymbolProvider
• workspaceSymbolProvider
• codeActionProvider
• codeLensProvider
• documentFormattingProvider
• documentRangeFormattingProvider
• documentOnTypeFormattingProvider
• renameProvider
• documentLinkProvider
• colorProvider
• colorPresentation
• foldingRangeProvider
• selectionRangeProvider
• executeCommandProvider

languageserver exposes the following settings via workspace/didChangeConfiguration

{
    "r.lsp.debug": {
      "type": "boolean",
      "default": false,
      "description": "Debug R Language Server"
    },
    "r.lsp.diagnostics": {
      "type": "boolean",
      "default": true,
      "description": "Enable Diagnostics"
    }
}

With lintr v2.0.0, the linters can be specified by creating the .lintr file at the project or home directory. Details can be found at lintr documentation. The option languageserver.default_linters is now deprecated in favor of the .lintr approach.

Server capabilities are defined in capabilities.R. Users could override the settings by specifiying languageserver.server_capabilities option in .Rprofile. For example, the following code will turn off definitionProvider,

options(
    languageserver.server_capabilities = list(
        definitionProvider = FALSE
    )
)

Please only use this option to disable providers and do not enable any providers that have not been implemented. Changing any other entries may cause unexpected behaviors on the server.

The language server uses styler to perform code formatting. It uses styler::tidyverse_style(indent_by = options$tabSize) as the default style where options is the formatting options.

The formatting style can be customized by specifying languageserver.formatting_style option which is supposed to be a function that accepts an options argument mentioned above. You could consider to put the code in .Rprofile.

styler::tidyverse_style provides numerous arguments to customize the formatting behavior. For example, to make it only work at indention scope:

options(languageserver.formatting_style = function(options) {
    styler::tidyverse_style(scope = "indention", indent_by = options$tabSize)
})

To disable assignment operator fix (replacing = with <-):

options(languageserver.formatting_style = function(options) {
    style <- styler::tidyverse_style(indent_by = options$tabSize)
    style$token$force_assignment_op <- NULL
    style
})

To further customize the formatting style, please refer to Customizing styler.

With styler v1.3, the formatting of top-level expressions can be cached by R.cache, which significantly improves the formatting performance by skipping the expressions that are known in cache to be already formatted. By default, the cache only works within the current session. To make it work across sessions, user must run the following command to perform a one-time authorization to create a permanent directory in user home in an interactive R session:

R.cache::getCachePath()

The first time the command is run, it will ask user whether to create a permanent cache directory. Type Y and enter, the cache directory will be created, and then all cache operations will be done across sessions so that formatted expressions could be remembered globally.

To check if a permanent directory is used or not, run the following command:

styler::cache_info()