Add lua (luajit) to rust example

luajit-to-rust/src/lib.rs

@@ -0,0 +1,4 @@
+#[no_mangle]
+pub extern fn double_input(input: i32) -> i32 {
+    input * 2
+}

luajit-to-rust/src/main.lua

@@ -0,0 +1,21 @@
+local ffi = require('ffi')
+
+local ext
+
+if ffi.os == 'Linux' then
+    ext = 'so'
+else
+    ext = 'dylib'
+end
+
+ffi.cdef[[
+int32_t double_input(int32_t input);
+]]
+
+local lib = ffi.load('target/debug/libdouble_input.' .. ext)
+local double_input = lib.double_input
+
+local input = 4
+local output = double_input(input)
+
+print(input .. " * 2 = " .. output)