Both of those choices have huge costs. SPARK may cost you actual money to use. It also takes longer to develop because of the large amount of safety checks. It

Both of those choices have huge costs. SPARK may cost you actual money to use. It also takes longer to develop because of the large amount of safety checks. It is suitable for writing code that runs on nuclear missiles. But you may not actually need that level of correctness and can just use Java instead. Rust's safety features focus on memory errors, which with Java is already solved for you. Another aspect of Rust's safety is preventing data races, which Java doesn't guarantee prevention of but SPARK does[1]. Rust covers a small subset of potential errors your program could have whereas SPARK could find errors throughout your code including in logic. Honestly though most "high-integrity fault tolerant distributed systems" out are written in C++, so just using something like Java is already a massive improvement in safety. But if you must choose one of these two, then it must be for a good reason, so choose SPARK. Rust occupies this middle zone which is neither specialized for extreme correctness nor convenience like Python. [1] https://docs.adacore.com/spark2014-docs/html/ug/en/source/concurrency.html#preventing-data-races https://docs.adacore.com/spark2014-docs/html/ug/en/source/co...