in scrooge-generator/src/main/scala/com/twitter/scrooge/backend/lua/LuaGenerator.scala [125:136]
def genPrimitiveType(t: FunctionType): CodeFragment = t match {
case Void => v("void")
case TBool => v("bool")
case TByte => v("byte")
case TDouble => v("double")
case TI16 => v("i16")
case TI32 => v("i32")
case TI64 => v("i64")
case TString => v("string")
case TBinary => v("binary")
case _ => v("")
}