languageserver: An implementation of the Language Server Protocol for R

languageserver is an implement 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

source("https://install-github.me/REditorSupport/languageserver")

Rmarkdown

The R package knitr is required to enable languageserver for Rmarkdown files. languageserver doesn't specify knitr as a dependency however, users may need to install it manually.

Language Clients

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()'],
    \ }

• EMacs: lsp-mode with settings

(lsp-register-client
    (make-lsp-client :new-connection
        (lsp-stdio-connection '("R" "--slave" "-e" "languageserver::run()"))
        :major-modes '(ess-r-mode inferior-ess-r-mode)
        :server-id 'lsp-R))

Services Implemented

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

• textDocumentSync (diagnostics)
• hoverProvider
• completionProvider
• signatureHelpProvider
• definitionProvider
• referencesProvider
• documentHighlightProvider
• documentSymbolProvider
• workspaceSymbolProvider
• codeActionProvider
• codeLensProvider
• documentFormattingProvider
• documentRangeFormattingProvider
• documentOnTypeFormattingProvider
• renameProvider
• documentLinkProvider
• executeCommandProvider

Settings

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"
    }
}

FAQ

Linters

With lintr master branch, the linters can be specified by creating the .lintr file at the project or home directory. Details can be found at lintr documentation.

Until a new version of lintr is released, you could consider the following settings in .Rprofile:

setHook(
    packageEvent("languageserver", "onLoad"),
    function(...) {
        options(languageserver.default_linters = lintr::with_defaults(
            line_length_linter = lintr::line_length_linter(100),
            object_usage_linter = NULL
        ))
    }
)

Customizing formatting style

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 suppoed 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.