Yeah, that is why I said TS (or something similar). TS made some decisions that make sense at the time, but do not help compilation. The complexity of its typing system is another problem. I'm pretty sure that it is Turing-complete. That doesn't remove feasibility, but it increases the complexity of compiling it by a whole lot. When you add onto this the fact that "the compiler is the spec," you really get bogged down. It would be much easier to recognize a sensible subset of TS. You could probably even have the type checker throw a WTFisThisGuyDoing flag and just immediately downgrade it to an any.