The luv library provides Lua access to the multi-platform libuv support library. In Neovim, this is accessible via vim.loop.
Key Concepts:
- Module Layout: The library is exposed as the
uv module. Most functions correspond to libuv C functions (e.g., uv_tcp_bind becomes uv.tcp_bind()). - Method-style API: Many functions support a method-style call. For example,
uv.tcp_bind(server, host, port) can be called as server:bind(host, port). - Synchronous vs Asynchronous:
- Functions with a callback are asynchronous; execution is deferred to the next loop iteration.
- Functions without a callback are synchronous and return results immediately.
- Some functions (FS and DNS) behave based on whether a callback is provided.
- Pseudo-Types:
fail: An assertable nil, string, string tuple.callable: A function, or a table/userdata with a __call metamethod.buffer: A string or a sequential table of strings.threadargs: Variable arguments (...) of type nil, boolean, number, string, or userdata.
local uv = vim.loop
-- TCP Echo Server Example
local server = uv.new_tcp()
server:bind("127.0.0.1", 1337)
server:listen(128, function (err)
assert(not err, err)
local client = uv.new_tcp()
server:accept(client)
client:read_start(function (err, chunk)
assert(not err, err)
if chunk then
client:write(chunk)
else
client:shutdown()
client:close()
end
end)
end)
print("TCP server listening at 127.0.0.1 port 1337")
uv.run() -- Explicit run call is necessary outside of luvit
