That is a great world. But considering that we still do not really know how to write e.g. generic code that operates on both immutable and mutable arrays, I think Julia is not there yet.

The other big thing missing in Julia that is IMO important here is more control over evaluation, like allowing lazy evaluation. You can build some of these features on top of Julia (e.g. https://github.com/RelationalAI-oss/Salsa.jl).

Math is usually not written with computation in mind, so some algorithm might e.g. re-evaluate f(x) multiple times. Compiler optimizations can help in some cases, as can a "dynamic" solution like memoization/caching. But again, I don't think Julia is "there" yet.