Custom Macros

Lulu allows you to define your own macros, which can then be used within your project or exported for other projects to use.

Defining a Macro

You define macros using the macro keyword. A definition consists of the macro name, a list of parameters, and a body.

• Parameters: Prefixed with a $ (e.g., $param). An underscore prefix ($_param) marks a parameter as optional.
• Body: The code that will be generated. You can use the parameters within the body.

-- This file can be named anything, e.g., _macros.lua

macro {
  -- Defines a macro named `add` with two required parameters
  add ($num1, $num2) {
    $num1 + $num2
  }
}

macro {
  -- Defines a macro named `hello` with one optional parameter
  hello ($_name) {
    print("Hello, " .. ($_name or "World"))
  }
}

Using Custom Macros

Once defined, you can use them like any other macro.

local sum = add! 2, { 3 } -- The last argument must be in braces
print(sum) -- Output: 5

hello! {} -- Output: Hello, World
hello! { "Makano" } -- Output: Hello, Makano

Exporting Macros

To make your macros available to other projects that depend on yours, you must export them in your lulu.conf.lua file using the macros field.

This field can be a string containing the macro definitions, or you can load them from a file.

-- lulu.conf.lua

-- Option 1: Inline string
macros = [[
  macro {
    add ($num1, $num2) { $num1 + $num2 }
  }
]]

-- Option 2: Load from a file (recommended)
macros = io.open("_macros.lua"):read("*a")

Now, if another project adds "github:your/project" to its dependencies, it will be able to use the add! macro.