Xo for Visual Studio Code

Language support for Xo: syntax highlighting, the xo lsp language server, and Xo's own debugger through xo debug --dap.

Features

Highlighting of .xo files and of xo fences in Markdown.
xo lsp: diagnostics and quick fixes, hover, go to definition, references, rename, document symbols, semantic highlighting and formatting.
Debugging (debug type xo): breakpoints, step in, over and out, the call stack, locals, threads and the program's tasks, on macOS arm64, Linux and Windows. Press F5 in an open .xo file to build its package and debug it, or add a configuration:
```
{
  "type": "xo",
  "request": "launch",
  "name": "Xo: debug the package",
  "program": "${workspaceFolder}",
  "args": [],
  "cwd": "${workspaceFolder}"
}
```
program is an executable built with its debug information (a plain xo build keeps it) or Xo source: a .xo file or a package directory, which the extension builds with xo build first. An attach takes processId (asked for when empty) and program, the process's executable; ending the session detaches and leaves the program running.

Requirements

An xo with xo lsp. Debugging needs Xo 0.40 or later (xo debug --dap); with an older xo the extension says so when a debug session starts, and highlighting and xo lsp still work. The extension uses, in order: the xo.path setting, xo on PATH, then bin/xo of an Xo checkout or .tools/bin/xo in a workspace folder or a directory above it.

Settings

Setting	Default	Meaning
`xo.path`	`""`	The xo binary; empty: found as above.
`xo.lsp.enabled`	`true`	Start `xo lsp`.

The command "Xo: Restart Language Server" restarts xo lsp (after a new xo, say). The "Xo" output channel shows which xo answers.

Development

npm ci
npm test                  # unit tests and the grammar's tokenization tests
XO_TEST_XO=$(which xo) npm test   # also debugs a program through xo debug --dap
npm run check:grammar     # the grammar's keywords against the newest Xo release's lexer
npm run check:grammar -- --lexer ../xo/compiler/lexer/token.xo   # against a checkout
npx @vscode/vsce package  # xo-0.1.0.vsix
code --install-extension xo-0.1.0.vsix

When Xo's lexical structure changes (a keyword, a literal form, a contextual word), update syntaxes/xo.tmLanguage.json and test/syntax.xo; check:grammar fails until the keywords agree with the release that has the change.

License

MIT, as Xo.

Xo Language