Pony Language Server

pony-lsp is the Pony Language Server. It communicates with editors via stdout/stdin using the Language Server Protocol. It is part of the ponylang/ponyc repository, built alongside the compiler.

Your editor launches the pony-lsp binary as a subprocess. See the editor configuration section for setup instructions.

Getting pony-lsp

pony-lsp is distributed via ponyup alongside ponyc. Installing a recent ponyc will also install pony-lsp. See the ponyc installation instructions for details.

Feature Support

Feature	Description	Supported since version
Diagnostics	Compiler errors and warnings published on file open and save	>= 0.60.5
Hover	Type information and documentation on hover	>= 0.60.5
Go To Definition	Jump to the definition of a symbol	>= 0.60.5
Document Symbols	List of symbols in the current file	>= 0.60.5
Document Highlight	All occurrences of the symbol under the cursor are highlighted simultaneously across the document	> 0.63.0
Find References	Show all references to the thing under the cursor	> 0.63.0
Inlay Hints	Display helpful hints in between the code. Mostly resolved types for expressions and variables.	> 0.63.0

Workspace Detection

pony-lsp needs to know the root of your project so it can resolve packages correctly. It determines this by scanning parent directories for a workspace root marker. The following are recognised as markers:

• corral.json (Pony’s dependency manager)
• bundle.json
• .git, .hg, .bzr, or .svn directories

Most Pony projects will have at least one of these already. If yours doesn’t, create an empty corral.json in the project root or initialise a Git repository there.

Settings

pony-lsp supports settings via workspace/configuration request and workspace/didChangeConfiguration notification.

Setting	Type	Example	Description
defines	Array[String]	["FOO", "BAR"]	Defines active during compilation, equivalent to the -D flag in ponyc
ponypath	Array[String]	["/path/to/pony/package"]	Additional package search paths for pony-lsp

The standard library is discovered automatically from the pony-lsp installation path. You only need ponypath if your project depends on packages outside the standard search locations.

Example settings:

{
  "defines": ["FOO", "BAR"],
  "ponypath": ["/path/to/pony/package", "/another/path"]
}

How to pass these settings depends on your editor. See the editor configuration sections below.

Editor Configuration

Helix

Getting Helix set up with pony-lsp is very easy. Add the following to your languages.toml.

[[language]]
name = "ponylang"
language-servers = [ "pony-lsp" ]
indent = { tab-width = 2, unit = "  " }

[language-server.pony-lsp]
command = "pony-lsp"
args = [""]

Project-Specific Defines

Defines are almost always project-specific. Rather than adding them to your global languages.toml, create a .helix/languages.toml in the project root:

[language-server.pony-lsp.config]
defines = [
  "MY_DEFINE_ONE",
  "MY_DEFINE_TWO",
]

Replace the example values with the actual defines your project needs.

Neovim

Configuration details are coming. If you use Neovim with pony-lsp, consider contributing to this section.

Visual Studio Code

To get pony-lsp working with Visual Studio Code, first install the Pony VS Code extension. Ensure pony-lsp is on your PATH — the extension will show an error if it isn’t found.

Open your VS Code settings to configure the extension (all options are optional):

{
  "pony.lsp.executable": "/usr/local/bin/pony-lsp",
  "pony.trace.server": "off",
  "pony-lsp.defines": ["FOO", "BAR"],
  "pony-lsp.ponypath": ["/path/to/pony/package1", "/path/to/pony/package2"]
}

pony.lsp.executable sets the path to pony-lsp if it isn’t on your PATH. pony.trace.server traces communication between VS Code and the language server ("off", "messages", or "verbose"). pony-lsp.defines and pony-lsp.ponypath are passed directly to pony-lsp.

For more details, see the Pony VS Code extension project documentation.

Zed

To get pony-lsp working with the Zed editor, first install the Pony Zed extension:

1. Open Zed
2. Press cmd-shift-x (macOS) or ctrl-shift-x (Linux/Windows)
3. Search for “Pony”
4. Click Install

Next, open your Zed settings to configure pony-lsp (all options are optional):

{
  "lsp": {
    "pony-lsp": {
      "settings": {
        "executable": "/pony/bin/pony-lsp",
        "ponypath": [
          "/path/to/project-a/packages",
          "/path/to/project-b/packages"
        ],
        "defines": [
          "MY_DEFINE_ONE",
          "MY_DEFINE_TWO"
        ]
      }
    }
  }
}

For more details, see the Pony Zed extension project documentation.