AFAIU antirez is mostly writing in C, a verbose language where "create a hashtable of x->y" turns into a wall of boilerplate. In high level languages the length diffrence between a precise specification and the actual code is much smaller.
This is done so that the programmer doesn't have to reason about it. Polonius makes the compiler accept code that's obviously valid, but the current borrow checker isn't sophisticated enough to declare it as safe.
I've bumped into this kind of problem when writing rust, at first it was hard to understand why the compiler doesn't accept my code.
The problem described in 2018 seems completely unrelated to downfall.
It looks like a potential optimization to the original spectre, doesn't even mention AVX gather instructions.
E. g. filter_vec_avx2 doesn't declare the loop variable i and stores input elements into the output instead of their indices. Or from_u32x8 has a DataType instead of __m256i and [u32; __m256i] instead of [u32; 8].
Meaningless because (adequately cooled) modern desktop CPUs mostly run near their boost clock in single threaded loads and somewhere between base and boost in multithreaded.
Haskell's IO monad actually has excellent exception support, including async exceptions and masking them in critical sections.
There are `Maybe` and `Either` and they're great at streamlining error handling in pure code, but when it comes to IO most libraries just throw exceptions (including the standard library).