README.md

PluginKit for Lua (LuaJIT)

This showcases the Clue PluginKit interface for Lua, which allows you to create native Lua extensions (.so) in Nim using LuaJIT's C API.

Prerequisites

• LuaJIT 2.1 or higher
• Nim 2.0 or higher
• Clue installed (nimble install clue)

Simple example

import clue/kits/luakit

luaModule do:
  name: "mylib"

  proc hello(name: string) =
    lua_pushstring(L, cstring("Hello " & name & " from Nim!"))
    return 1

  proc add(a: int, b: int) =
    lua_pushinteger(L, a + b)
    return 1

  proc is_positive(n: float) =
    lua_pushboolean(L, cint(n > 0.0))
    return 1

Build the extension

nim c --app:lib --out:"build/mylib.so" plugin_example.nim

Or with the included .nims:

nim c plugin_example.nims

Test the extension

local mylib = require "mylib"

print(mylib.hello("Lua"))
print(mylib.greet("World"))
print("21 doubled = " .. mylib.double(21))
print("3 + 7 = " .. mylib.add(3, 7))
print("3.14 positive?", mylib.is_positive(3.14))

Run with:

LUA_CPATH="./build/?.so;;" luajit test_example.lua

Debugging

Use -d:clueDebugExtension when compiling to see the generated Nim code.

nim c -d:clueDebugExtension --app:lib --out:"build/mylib.so" plugin_example.nim