LuaJIT's FFI library

LuaJIT's FFI library makes it easy to call C functions and C data structures by parsing C declarations:

local ffi = require("ffi")
Load LuaJIT's FF library
ffi.cdef[[
int printf(const char *fmt, ...);
]]
Add a C declaration for the function.
ffi.C.printf("Hello %s!", "world")

Call the named C function. Simple!