Tour of Lua

Exposing Elixir with deflua

You'll learn: Define a module with use Lua.API + deflua, then load it with Lua.load_api/2.

deflua turns an Elixir function into a Lua-callable. The optional scope: puts it under a namespace — scope: "pricing" exposes pricing.discount(…). Lua.load_api(lua, MyModule) registers the module on the VM. The Lua side just calls a function; the Elixir side runs the body.

Elixir · your app

Reference only

defmodule Pricing do
  use Lua.API, scope: "pricing"

  deflua discount(amount, pct) do
    amount * (1 - pct / 100)
  end
end

lua = Lua.new() |> Lua.load_api(Pricing)
{[total], _} = Lua.eval!(lua, ~S|return pricing.discount(100, 15)|)
# total = 85.0

deflua.lua

Output idle

Hit Run to execute.

Try it: Add deflua tax(amount, rate) to Pricing, returning amount * rate. Call pricing.tax(85, 0.08) from Lua — remember to extend the playground stub too.

Exposing Elixir with deflua

Exposing Elixir with `deflua`