I disagree. I like playing around in Rust, but it is near impossible to reason about what instructions will end up being fed to your CPU without having the comp

I disagree. I like playing around in Rust, but it is near impossible to reason about what instructions will end up being fed to your CPU without having the compiler emit the underlying assembly. And that makes it very difficult to understand the performance of your code. Just a few days ago I couldn't wrestle the compiler into unrolling a loop (because of a get_unchecked that was hard to reason about), dropping performance of the entire data structure to as little as 30% of a quick proof of concept implementation. The asserts are powerful tools, but only if you can figure out why the compiler is not behaving nicely and how to construct the conditions that will convince it...