Lua is a dynamically typed language, with only a small selection of primitive types. Any aggregate or otherwise complex types must use tables (i.e., dictionaries/associative arrays) in some form, which will significantly impact the performance of field/method access as well as the efficiency of data storage (and thus cache usage). LuaJIT’s foreign function interface (FFI) let’s us work around those limitations by offering us the ability to use C declarations to define new types with much greater control and efficiency. In this blog post, I’ll share how, for my Worldbuilder project, I used the FFI to implement a fairly performant fixed point number type. Public domain source code can be downloaded here. (more…)