Language setups

Working recipes for the usual suspects: what to install for each language's server and formatters, and the configuration that wires them up. Every snippet goes in config.json (see Configuration) or, equivalently, through Settings ▸ Language Servers — these are the hand-edited forms because they are easier to copy. Servers listed here match the built-in registry, so installing the tool is usually enough; the lsp entries below are only needed when you want a different server than the default.

Install lines assume Homebrew on macOS; on Linux, your package manager or the language's own installer does the same job.

Python

brew install pyright ruff black

(or npm install -g pyright, pip install ruff black.)

Pyright is the default server. Ruff fixes and Black formats on every save:

{
  "preprocessors": {
    "defaults": { "python": ["ruff check --fix-only -", "black -"] }
  }
}

Prefer python-lsp-server? Install it (pip install python-lsp-server) and point the language at it:

{ "lsp": { "defaults": { "python": "pylsp" } } }

Go

brew install go gopls

gopls is found automatically. gofmt ships with Go itself:

{ "preprocessors": { "defaults": { "go": ["gofmt"] } } }

Swap in goimports (go install golang.org/x/tools/cmd/goimports@latest) to also manage imports on save.

Rust

rustup component add rust-analyzer rustfmt

rust-analyzer is the default server. rustfmt reads stdin when called plainly:

{ "preprocessors": { "defaults": { "rust": ["rustfmt"] } } }

JavaScript

npm install -g typescript typescript-language-server prettier

typescript-language-server is the default server. Prettier picks its parser from the file name, so hand it the document's real one — {filename} expands to it:

{
  "preprocessors": {
    "defaults": { "javascript": ["prettier --stdin-filepath {filename}"] }
  }
}

C

brew install llvm

clangd and clang-format both come with LLVM (Xcode's command-line tools also carry a clangd). clang-format reads stdin by default and picks up the project's .clang-format:

{ "preprocessors": { "defaults": { "c": ["clang-format"] } } }

Swift

sourcekit-lsp ships with Xcode and is found automatically. swift-format comes with recent toolchains:

{ "preprocessors": { "defaults": { "swift": ["swift format"] } } }

Shell

brew install bash-language-server shfmt shellcheck

{ "preprocessors": { "defaults": { "bash": ["shfmt"] } } }

JSON / YAML / Markdown

Prettier handles all three; Markdown also gets the built-in preview and prose spell checking without any setup:

{
  "preprocessors": {
    "defaults": {
      "json": ["prettier --stdin-filepath {filename}"],
      "yaml": ["prettier --stdin-filepath {filename}"],
      "markdown": ["prettier --stdin-filepath {filename}"]
    }
  }
}

Checking a setup

Open a file of the language and watch the window subtitle: problem counts appear when the server answers. When nothing happens, the Language servers page covers the debug log (~/Library/Logs/Textchum/lsp.log), the PATH rules, and the ctags fallback for projects without a server. Preprocessor failures always surface as an alert naming the command and its stderr — a chain can never eat a save silently.