Yeah, I don't buy the justification versus Julia because of community size either, given most of Swift's community has little to do with data science. The document even says as much, contradicting that rationale, later on.

As someone who uses TF heavily, I would be much more excited about this project if they'd chosen Julia. Swift's tooling isn't great, and I already have a foot in one language with an immature data science ecosystem (Rust).

How is Rust-Julia interop?

Julia's `ccall` is great in terms of overhead[0], so calling Rust shared libraries is not a problem. On the Rust side, it took me a while to figure out passing in pointers, and then constructing slices via from_raw_parts[_mut], so that I can transition to safe Rust. Perhaps that is obvious to more experienced Rust programmers, but I was left with the impression that receiving pointers and crunching numbers is not yet a common application for Rust (unlike C, C++, or Fortran). Meaning there is not a lot of introductory material coming from that angle at the moment. Additionally, to get good vectorization seems to require nightly and a fastfloat[1] library. In particular, you'd want associative math / fp-contract for fma and SIMD instructions, and perhaps fno-math-errno to turn off branches in functions like sqrt.

I imagine calling Rust from Julia will be much more common than calling Julia from Rust. I know approximately nothing about this, but there are plenty of questions about embedding Julia into C/C++[2][3]. May be similar for Rust.

[0] https://github.com/dyu/ffi-overhead [1] https://github.com/robsmith11/fastfloat [2] https://discourse.julialang.org/t/support-with-embedding-jul... [3] https://discourse.julialang.org/t/api-reference-for-julia-em...