Comment by wrathofmonads

The real barrier is the C++ ecosystem. It represents the cost of losing decades of optimized, highly integrated, high-performance libraries. C++ maps almost perfectly to the hardware with minimal overhead, and it remains at the forefront of the AI revolution. It is the true engine behind Python scientific libs and even Julia (ex. EnzymeAD). Rust does not offer advantages that would meaningfully improve how we approach HPC. Once you layer the necessary unsafe operations, C++ code in practice becomes mostly functional and immutable, and lifetimes matter less beyond a certain threshold when building complex HPC simulations. Or even outsourced to a scripting layer with Python.