I have departed from the traditional approach of implementing a Scheme interpreter in Scheme itself because I wanted to avoid possible confusions between the defined language and the defining language. This has made a lot of the concepts clearer. The evaluator is written in continuation-passing style, which is easily done in Lua because the latter has tail-call optimisations. This way it is easier to reify continuations to first-class values.

I have also added a few primitives to allow me to run some examples, as the factorial and fibonacci functions. More primitives can be easily added if desired.