Lambda-the-Ultimate.org is admittedly over my head at times, but sometimes jumping into the deep end is the best way to learn to swim. It is a good place to hang out for aspiring language designers. They do have their own jargon at that site which can be a bit impenetrable at times, so I recently purchased the Types and Programming Languages book by Benjamin C. Pierce.

What is happening right now with Cat is that I am trying to merge static type-checking and dynamic type-checking in a single language. Not really anything new when you think about it. many languages support or at least provide the tools to implement variant types. What I am doing a bit different is that types have become first class values in Cat, and the core language is dynamically typed. At the same time Cat supports, and in fact encourages, type annotations, and optional compilation.

If a Cat program is compiled then the compiler is expected to precompute the type-expressions the same way compilers for other language precompute constant integer expressions. Like how 2 + 5 will often be replaced with the value 7 at compile-time.