lye for VS Code

A thin wrapper: it starts the lye language server and lets it answer. Diagnostics, hover, go-to-definition, document symbols, semantic tokens and completion all come from the server, so this extension carries no language logic of its own.

Requirements

The lye executable must be on your PATH. If it is somewhere else, set lye.serverPath to its full path. The extension reports the path it tried when the server does not start.

Install lye by building it from the repository:

tools/compile.sh   # writes packages/lye-lsp/lye-lsp

The script compiles a snapshot of the working tree in a temporary directory. Use lde compile -C packages/lye-lsp directly only in a checkout that has never run the tests: the test suite writes fixtures into packages/lye-lsp/target/, and the compiler would read them as source.

Settings

Changing lye.serverPath restarts the server.

Plugin languages

A workspace can name a plugin that adds a language with its own file extension. When the workspace contains a lye.json, the extension starts even if no Lua file is open; the server reads the plugins, and registers their extensions with VS Code through LSP dynamic document registration. Opening a .toy file (or any extension a plugin claims) then gets the same diagnostics, hover, completion and semantic tokens as a .lua file.

Development

npm install
npm run compile

Then press F5 to launch an Extension Development Host with the extension loaded.

To build a .vsix:

npm run package

Measuring what an editor waits for

npm run benchmark drives the server the way the client does — the same arguments, the same framing, an open document and the requests an editor makes — and prints the round trip for each:

LYE_BINARY=../lye-lsp/lye-lsp npm run benchmark -- --iterations 50
LYE_BINARY=../lye-lsp/lye-lsp npm run benchmark -- --source ../some/big.lua

Each row also prints what the request answered, so a number is never about an empty reply. For the same measurement through a real editor, tests/benchmark.js runs inside a headless VS Code instance as an extension-host test; see "Running it headless" below.

Comparing with other servers

npm run compare runs the same requests through lye, LuaLS and emmylua-analyzer, and prints what each one answered and how long it took — plus the capabilities each advertises, which is the feature list a client can rely on:

npm run compare -- --lye ../lye-lsp/lye-lsp --luals ~/Tools/lua-language-server \
	--emmylua ~/.local/bin/emmylua_ls --iterations 10 --json /tmp/compare.json

Every row prints a summary of the answer, so a row of dashes means the server did not answer rather than that it answered quickly. One trap is recorded in the script: a language server sends requests of its own (registering capabilities, asking for configuration) and a client that stays silent makes it wait — LuaLS will not analyse anything until its client/registerCapability is answered.

Running it headless

Both the smoke test and the in-editor benchmark need no display. VS Code runs with --ozone-platform=headless, which is enough for the extension host:

code --user-data-dir=/tmp/lye-vscode/user --extensions-dir=/tmp/lye-vscode/ext \
	--ozone-platform=headless --disable-gpu --no-sandbox --disable-workspace-trust \
	--extensionDevelopmentPath=$PWD --extensionTestsPath=$PWD/tests/benchmark.js \
	/path/to/a/workspace

tests/benchmark.js is that test: it activates the extension, opens a file, and times the commands VS Code itself runs for hover, completion, definitions, symbols and the round trip from an edit to the diagnostics it draws. It writes JSON to LYE_BENCH_OUT, and LYE_BENCH_FILE picks the file to open.

Layout

With another Lua extension installed

This extension contributes the lua language id, and so does every other Lua extension. Two language servers attached to the same document both publish diagnostics, hover, completion and semantic tokens, and the editor merges what they say — which makes it hard to tell which server answered. Disable the others for the workspace if you want to see lye alone:

Command Palette → Extensions: Disable (Workspace), or a workspace profile with only lye enabled.