On the Julia front, I believe the evolving effect system may help a little bit with obtaining/surfacing that information. JET.jl should be able to solve the typ

On the Julia front, I believe the evolving effect system may help a little bit with obtaining/surfacing that information. JET.jl should be able to solve the type stability (inference) one from a whole-of-program perspective. We have `@inferred` for unit tests. The macros would be a cool addition - I wonder if they would get overused though? I agree that Julia takes the idea of optimization to the extreme - it's semantically a very dynamic language and only fast due to non-semantically guaranteed optimization. On the other hand, getting access to the generated IR, LLVM and assembly and iteratively improving it is far easier than any other language I've seen.