PureScript language server

Node-based Language Server Protocol server for PureScript based on the PureScript IDE server (aka psc-ide / purs ide server). Used as the vscode plugin backend but should be compatible with other Language Server Client implementations.

The language server is a wrapper around the IDE server included as part of the compiler distribution, providing editing assistance and build features according to support available. This means that the server will start its own purs ide server instance to talk to for the project directory it is started in.

Features

Completion provider
Definition provider
Formatting provider
Document & workspace symbol providers
Hover provider
Code action provider
- Compiler fix suggestions for imports/missing types
Build on save (via IDE server "fast rebuild" facility, certain limitations apply)
- Provides diagnostics
Commands
- Build (full build via purs compile / configured build command) - provides diagnostics
- Case split
- Add clause
- Replace suggestion
- Add completion import
- Start IDE server
- Stop IDE server
- Restart IDE server
Config
- purescript.*

Usage

This LSP implmementation is consumed by vscode and Atom plugins as a node module, and bundled along with those plugins.

To use with another LSP client, you will want to install this either globally or locally for npm, e.g.

npm i -g purescript-language-server

And then use the resulting executable, e.g. purescript-language-server --stdio.

This language server is based on vscode-languageserver-node which means it should support --stdio, --socket=[number], --node-ipc or --pipe methods of communication, see vscode-languageserver-node for details.

Version support policy

PureScript compiler version support is as follows:

The current minor version of the compiler is supported at all patch versions (e.g. 0.14.xx)
The previous minor version of the compiler is supported at the latest patch version (e.g. 0.13.8) for new functionality, and where possible all patch versions for existing functionality
Any older compiler versions are not officially supported - they may continue to work and will not be intentionally broken, but no particular effort will be made for continued support in the face of API changes

Formatting provider

The purescript-language-server comes with support for formatting PureScript code via several external tools, exposed as a standard LSP formatting provider. When a formatting operation is requested, purescript-language-server will attempt to find the configured tool via its standard name in your $PATH (or the local npm install path if purescript.addNpmPath is set).

The formatting tool is selected via purescript.formatter, with the following options

No formatter - simply leave the setting unset or empty (default)
purs-tidy (or simply tidy). If you do not have any existing preferences this would be the suggested pick.
pose
purty

VSCode

Use vscode-ide-purescript.

Atom

Use atom-ide-purescript.

Neovim’s built-in language server + nvim-lspconfig

As of 0.5.0, Neovim has a built-in language server client. A popular plugin to help with configuring this server is nvim-lspconfig. This plugin includes purescriptls which will automatically find and root the language server as well as connect PSCIDE, etc. (for more info, read the config). To use, add this to your init.lua or inside a EOF << lua … EOF block in your init.vim.

nvim_lsp.purescriptls.setup {
  " Your personal on_attach function referenced before to include
  " keymaps & other ls options
  on_attach = on_attach,
  settings = {
    purescript = {
      addSpagoSources = true -- e.g. any purescript language-server config here
    }
  },
  flags = {
    debounce_text_changes = 150,
  }
}

NeoVim plugin that adds more commands, designed to supplement built-in language server

Use nvimmer-ps.

Vim/LSP

Auto configuration with vim-lsp-settings

Vim/CoC

Configuration with coc.nvim

Run :CocConfig and add "purescript" in the "languageserver" section as follows:

  "languageserver": {
    "purescript": {
      "command": "purescript-language-server",
      "args": ["--stdio"],
      "filetypes": ["purescript"],
      "trace.server": "off",
      "rootPatterns": ["bower.json", "psc-package.json", "spago.dhall"],
      "settings": {
        "purescript": {
          "addSpagoSources": true,
          "addNpmPath": true, // Set to true if using a local purty install for formatting
          "formatter": "purs-tidy"
          // etc
        }
      }
    }
  }

CoC can be configured to format your code using the purescript-language-server's formatting provider, which is backed by purty. If you don't have CoC-based code formatting setup in CoC already, you can add a command or key mapping like this:

command! -nargs=0  Format      :call CocAction('format')
nmap               <leader>f   :Format<cr>

If you want the formatter to run on save, run :CocConfig and add "purescript" to the "coc.preferences.formatOnSaveFiletypes":

  "coc.preferences.formatOnSaveFiletypes": [
    // ...other languages
    "purescript"
  ]

You can also organize PureScript imports in Vim with a command and/or key mapping like this:

command! -nargs=0  OrganizeImports :call CocAction('runCommand', 'editor.action.organizeImport')
nmap               <leader>o       :OrganizeImports<cr>

Vim/LanguageClient_neovim

Use vimmer-ps.

Other clients

Config may be supplied via client-push on startup (workspace.didChangeConfiguration), server-request (workspace.configuration), or at last resort by JSON object on the command line with --config option.

Config

See config defined in vscode plugin.

Usage with alternate backends

When using the language server together with alternate backends, the only requirement is to stop purs ide server from attempting to generate JS when rebuilding, this is done via the config

"purescript.codegenTargets": [ "corefn" ]

(and you should make sure the build command is in accordance with that, if used, eg specify backend in spago config).

Commands

Various commands are provided. Some are triggered via completion etc, some must be called explicitly from a LSP client.

`purescript.build`

No arguments. Provides diagnostics.

`purescript.startPscIde`

No arguments. Start IDE server according to configuration.

`purescript.stopPscIde`

No arguments. Stop running IDE server.

`purescript.restartPscIde`

No arguments. Stop any running IDE server then start a new one according to configuration.

`purescript.addCompletionImport`

Arguments: identifier, module, document URI.

`purescript.addModuleImport`

Arguments: module, qualifier, document URI.

`purescript.getAvailableModules`

No arguments. Get list of available modules.

`purescript.replaceSuggestion`

Arguments: document URI, replacement, replacement range.

`purescript.search`

Flex search for identifier.

Arguments: search text.

`purescript.fixTypo`

Arguments: document URI, line, character.

`purescript.caseSplit-explicit`

(Used to back the case split command in VS Code UI).

Arguments: document URI, line, character, type.

`purescript.addClause-explicit`

(Used to back the add clause command in VS Code UI).