Code Hygiene

In this chapter, we'll run Lux's type checker, linter, and formatter on our project to catch issues and keep the code consistent.

Type checking

Lux can statically type-check your Lua code using LuaCATS annotations. Let's run it on our project:

lx check

Everything should pass with no errors.

Now let's see what happens when there's a type mismatch. Open src/has_hello.lua and change the input parameter annotation from string to integer:

---@param input integer
local function has_hello(input)

Run lx check again:

lx check

This time Lux should report that string:lower() can't be called on an integer. Go ahead and change the annotation back to string.

Linting with lx lint

Lux uses luacheck to detect potential errors and style issues. Let's try it on our project:

lx lint

No issues should be reported.

Now let's introduce one. Open src/has_hello.lua and add an unused local variable:

local unused = true
local function has_hello(input)

Run lx lint again:

lx lint

Lux should report that unused is assigned but never used. Remove the line and re-run to confirm the warning is gone.

Formatting with lx fmt

Let's format our code:

lx fmt

Feel free to take a look at the changes lx fmt made to our code!

Now that our code is nice and shiny, we're ready to move onto the final step: publishing our code to luarocks.org!